Chapter 34 — Anti-Cancer Drugs Part II — Module 4 — Immune Checkpoint Inhibitors, Hormonal Oncology, and CAR-T Cell Therapy: Foundational Recall
1. A clinician must distinguish the phase of the T-cell response at which CTLA-4 and PD-1 checkpoint blockade act, because this distinction underlies the differing efficacy and toxicity of the two drug classes. Which statement most precisely characterizes the predominant site and phase of action of each checkpoint?
A) CTLA-4 blockade acts in the effector phase at the tumor site, while PD-1/PD-L1 blockade acts during priming in lymph nodes.
B) Both CTLA-4 and PD-1/PD-L1 blockade act exclusively during the priming phase within lymph nodes.
C) CTLA-4 blockade acts predominantly during the priming phase in lymph nodes, while PD-1/PD-L1 blockade acts predominantly in the effector phase at the tumor in peripheral tissue.
D) Both CTLA-4 and PD-1/PD-L1 blockade act exclusively in the effector phase at the tumor site.
E) CTLA-4 blockade acts on B-cell maturation in bone marrow, while PD-1/PD-L1 blockade acts on natural killer cells in the spleen.
ANSWER: C
Rationale:
CTLA-4 (cytotoxic T-lymphocyte-associated protein 4) competes with the co-stimulatory receptor CD28 during the priming phase, when naive T cells are first activated by antigen-presenting cells in lymph nodes; blocking it (ipilimumab) broadens the activated T-cell repertoire. PD-1 (programmed death 1) and its ligand PD-L1 act later, in the effector phase, restraining activated T cells when they encounter the tumor in peripheral tissue; blocking that axis (nivolumab, pembrolizumab) restores effector activity at the tumor. This phase distinction is the conceptual basis for the greater toxicity of CTLA-4 blockade.
Option A: Option A inverts the two phases.
Option B: Option B is incorrect because only CTLA-4 is predominantly a priming-phase checkpoint; the PD-1 axis is predominantly effector-phase.
Option D: Option D is incorrect because CTLA-4 is not predominantly an effector-phase, tumor-site checkpoint.
Option E: Option E is incorrect because both are T-cell checkpoints, not regulators of B-cell maturation or natural killer cells.
2. PD-1 inhibitors and PD-L1 inhibitors both interrupt the same inhibitory axis but bind different molecules. Which statement correctly distinguishes the target of a PD-1 inhibitor from that of a PD-L1 inhibitor?
A) A PD-1 inhibitor binds the PD-1 receptor on the T cell, whereas a PD-L1 inhibitor binds the PD-L1 ligand expressed on tumor cells and antigen-presenting cells.
B) A PD-1 inhibitor binds the ligand on tumor cells, whereas a PD-L1 inhibitor binds the receptor on the T cell.
C) Both PD-1 and PD-L1 inhibitors bind CTLA-4 on the T-cell surface.
D) A PD-1 inhibitor binds an intracellular kinase, whereas a PD-L1 inhibitor binds a nuclear transcription factor.
E) Both PD-1 and PD-L1 inhibitors bind the same molecule and differ only in their dosing schedule.
ANSWER: A
Rationale:
PD-1 is the inhibitory receptor on the T cell; PD-L1 is one of its ligands, expressed on tumor cells and antigen-presenting cells. A PD-1 inhibitor (nivolumab, pembrolizumab) binds the receptor on the T cell; a PD-L1 inhibitor (atezolizumab, durvalumab) binds the ligand on the tumor side. Both block engagement of the axis, but at opposite ends of the receptor-ligand pair.
Option B: Option B inverts the two targets.
Option C: Option C is incorrect because neither agent binds CTLA-4, which is a separate checkpoint.
Option D: Option D is incorrect because these are cell-surface antibody targets, not an intracellular kinase or a transcription factor.
Option E: Option E is incorrect because the two classes bind different molecules (receptor versus ligand), not the same molecule.
3. A patient on combination ipilimumab-nivolumab develops grade 3 immune-mediated colitis (more than 6 stools per day above baseline, severe abdominal pain). After infection is excluded, which management sequence is correct?
A) Continue both agents at full dose and start loperamide as definitive therapy.
B) Start oral antibiotics as the definitive treatment and continue both checkpoint inhibitors.
C) Begin low-dose prednisone at 0.25 mg/kg/day and continue ipilimumab.
D) Permanently discontinue ipilimumab, start high-dose corticosteroids (methylprednisolone 1-2 mg/kg/day), and add infliximab if there is no improvement within about 3 days.
E) Administer infliximab as monotherapy without corticosteroids and rechallenge with ipilimumab in one week.
ANSWER: D
Rationale:
Grade 3 immune colitis requires permanent discontinuation of the CTLA-4 agent (ipilimumab), prompt high-dose systemic corticosteroids (methylprednisolone 1-2 mg/kg/day), and escalation to infliximab — the steroid-sparing agent of choice for colitis — if there is inadequate response within roughly 72 hours. This reflects the standard severity-based algorithm.
Option A: Option A is incorrect and unsafe because continuing the drugs and relying on an antimotility agent does not treat the immune inflammation and risks perforation.
Option B: Option B is incorrect because antibiotics treat infection, which must be excluded but is not the cause of immune colitis.
Option C: Option C is incorrect because grade 3 colitis requires high-dose (roughly 1-2 mg/kg/day), not subtherapeutic, corticosteroids, and the offending agent should not be continued.
Option E: Option E is incorrect because infliximab is added to corticosteroids rather than used alone, and rechallenge with ipilimumab after grade 3 colitis is contraindicated.
4. A patient receiving a PD-1 inhibitor develops grade 3 immune-mediated hepatitis (transaminases more than 5 times the upper limit of normal). Corticosteroids at 1-2 mg/kg/day are started but the transaminases continue to rise. Which steroid-sparing agent is appropriate, and which must be avoided?
A) Add infliximab; avoid mycophenolate mofetil because it worsens hepatic inflammation.
B) Add mycophenolate mofetil; avoid infliximab because of its own potential for hepatotoxicity.
C) Add infliximab; mycophenolate mofetil has no role in any immune-related adverse event.
D) Add tocilizumab; avoid all corticosteroids because they are hepatotoxic.
E) Add a somatostatin analog; avoid both mycophenolate and infliximab.
ANSWER: B
Rationale:
For steroid-refractory immune hepatitis, mycophenolate mofetil is the steroid-sparing agent of choice, while infliximab is avoided because anti-TNF therapy carries its own risk of hepatotoxicity. This is the key discrimination from immune colitis, where infliximab is appropriate.
Option A: Option A is incorrect because it reverses the correct choice — infliximab is the agent to avoid in hepatitis, not mycophenolate.
Option C: Option C is incorrect because mycophenolate does have a defined role (notably in hepatitis), and infliximab is contraindicated here.
Option D: Option D is incorrect because corticosteroids are the first-line treatment for immune hepatitis, not a contraindicated class, and tocilizumab is not the standard agent.
Option E: Option E is incorrect because somatostatin analogs treat neuroendocrine tumors and have no role in immune hepatitis.
5. A patient on pembrolizumab develops new dyspnea, and chest CT shows new bilateral ground-glass opacities. Immune-mediated pneumonitis is suspected. Which combination of steps reflects correct management?
A) Begin empiric antibiotics alone, continue pembrolizumab, and avoid corticosteroids entirely.
B) Resume pembrolizumab immediately after starting steroids, regardless of pneumonitis grade.
C) Start corticosteroids only if the patient becomes hypoxic at rest, and otherwise take no action.
D) Treat with tocilizumab as first-line therapy and continue pembrolizumab at full dose.
E) Evaluate to exclude infection (including bronchoscopy when appropriate), start corticosteroids 1-2 mg/kg/day for grade 2 or higher, and permanently discontinue the checkpoint inhibitor for grade 3-4 disease.
ANSWER: E
Rationale:
Immune pneumonitis requires exclusion of infection (bronchoscopy with lavage when feasible), corticosteroids at 1-2 mg/kg/day for grade 2 or higher, holding the drug for grade 2, and permanent discontinuation for grade 3-4 disease, because high-grade pneumonitis can be fatal.
Option A: Option A is incorrect because withholding corticosteroids and continuing the drug ignores the immune etiology and the need to hold or stop therapy.
Option B: Option B is incorrect because rechallenge depends on grade and recovery; high-grade pneumonitis precludes resumption.
Option C: Option C is incorrect because grade 2 disease (symptomatic, not necessarily hypoxic at rest) already warrants corticosteroids and holding the drug.
Option D: Option D is incorrect because tocilizumab is not first-line for pneumonitis (corticosteroids are), and the drug should not be continued at full dose.
6. A patient on a checkpoint inhibitor presents with hypotension, vomiting, hyponatremia, and hyperkalemia, raising concern for adrenal crisis from immune-mediated hypophysitis or primary adrenal failure. Which statement reflects correct management of the endocrine emergency versus the non-urgent presentation?
A) In suspected adrenal crisis, give IV hydrocortisone immediately without waiting for test results; in a non-urgent presentation, draw ACTH and cortisol before starting steroids to preserve diagnostic utility.
B) In suspected adrenal crisis, withhold all steroids until ACTH and cortisol results return; in non-urgent cases, give empiric high-dose steroids before any testing.
C) In all cases, give levothyroxine first and defer corticosteroids until thyroid studies return.
D) In suspected adrenal crisis, the first step is to increase the checkpoint inhibitor dose to restore adrenal output.
E) In all cases, start fludrocortisone alone, as glucocorticoid replacement is unnecessary in checkpoint-induced adrenal insufficiency.
ANSWER: A
Rationale:
Adrenal crisis is life-threatening: give stress-dose IV hydrocortisone immediately and do not wait for confirmatory testing. When the presentation is non-urgent, draw ACTH (adrenocorticotropic hormone) and cortisol before starting glucocorticoids so the diagnostic axis can be interpreted. This contrast — treat first in crisis, test first when stable — is the core discrimination.
Option B: Option B inverts both halves of the correct approach.
Option C: Option C is incorrect and dangerous because giving levothyroxine before glucocorticoid replacement in coexisting adrenal insufficiency can precipitate crisis.
Option D: Option D is incorrect because raising the checkpoint inhibitor dose does not restore adrenal function and may worsen gland injury.
Option E: Option E is incorrect because glucocorticoid (hydrocortisone) replacement is the essential treatment; mineralocorticoid alone is inadequate.
7. A patient on pembrolizumab is found to have a suppressed TSH with an elevated free T4 and a heart rate of 110 beats per minute. The picture is checkpoint inhibitor-induced thyroiditis. Which statement best captures the expected course and correct initial management?
A) This represents Graves disease; start methimazole and discontinue pembrolizumab permanently.
B) The hyperthyroidism is permanent; commit to lifelong antithyroid drug therapy and radioactive iodine.
C) Start levothyroxine now to correct the elevated free T4 and stop monitoring thyroid function.
D) The hyperthyroid phase is transient (release of preformed hormone); treat symptoms with a beta-blocker, continue pembrolizumab, and monitor, anticipating progression to hypothyroidism within several weeks.
E) Begin high-dose corticosteroids as first-line therapy for the hyperthyroid phase and discontinue pembrolizumab.
ANSWER: D
Rationale:
Checkpoint inhibitor thyroiditis typically begins with a transient hyperthyroid phase from release of preformed thyroid hormone as the gland is inflamed; management is symptomatic with a beta-blocker, the drug is continued, and the patient is monitored because the gland commonly becomes hypothyroid within several weeks.
Option A: Option A is incorrect because this is destructive thyroiditis, not Graves disease, and antithyroid drugs are not the treatment; the drug need not be permanently stopped.
Option B: Option B is incorrect because the hyperthyroid phase is transient, not permanent.
Option C: Option C is incorrect because levothyroxine treats hypothyroidism and would aggravate the current hyperthyroid phase; monitoring must continue.
Option E: Option E is incorrect because corticosteroids are not first-line for routine thyroiditis, which is self-limited and managed symptomatically.
8. Three biomarkers are used to predict response to PD-1 blockade: PD-L1 expression, tumor mutational burden (TMB, the number of mutations per megabase of tumor DNA), and microsatellite instability-high/mismatch-repair-deficient (MSI-H/dMMR) status. Which statement most precisely distinguishes these markers?
A) PD-L1 expression and TMB are identical measurements reported in different units.
B) MSI-H/dMMR status reflects a defect in DNA mismatch repair that generates a high neoantigen load and predicts response to PD-1 blockade across multiple tumor types, distinct from quantifying PD-L1 protein expression or counting total mutations as TMB.
C) MSI-H/dMMR status measures the percentage of tumor cells expressing PD-L1 protein on their surface.
D) TMB is a measure of how strongly the PD-1 receptor is expressed on circulating T cells.
E) PD-L1 expression predicts response only in MSI-H tumors and is meaningless in all other settings.
ANSWER: B
Rationale:
MSI-H/dMMR reflects loss of mismatch-repair function, which produces many mutations and neoantigens and predicts response to PD-1 blockade in a tissue-agnostic manner. This is mechanistically and methodologically distinct from PD-L1 immunohistochemistry (which quantifies ligand protein) and from TMB (which counts mutations per megabase).
Option A: Option A is incorrect because PD-L1 expression and TMB measure entirely different things (ligand protein versus mutation count).
Option C: Option C is incorrect because MSI-H/dMMR is a DNA-repair status, not a measure of PD-L1 protein.
Option D: Option D is incorrect because TMB quantifies tumor mutations, not PD-1 receptor density on T cells.
Option E: Option E is incorrect because PD-L1 expression has predictive value in numerous non-MSI-H settings.
9. A man with metastatic prostate cancer and high tumor burden, including vertebral metastases, is to begin a GnRH agonist (leuprolide). Knowing the pharmacology of GnRH agonists, which intervention is required at initiation, and why?
A) No additional drug is required, because GnRH agonists lower testosterone within hours of the first dose.
B) Add finasteride at initiation to block the conversion of testosterone to dihydrotestosterone during the surge.
C) Add an aromatase inhibitor to prevent the estrogen surge that GnRH agonists cause.
D) Begin lifelong corticosteroids to suppress the pituitary before the first dose.
E) Co-prescribe a short course of an antiandrogen (for example, bicalutamide for about 4 weeks) starting before and during initiation to prevent the testosterone flare from worsening disease and risking spinal cord compression.
ANSWER: E
Rationale:
Continuous GnRH receptor stimulation initially raises luteinizing hormone and testosterone (the flare) before downregulation lowers testosterone over one to two weeks; in a patient with high burden and vertebral metastases, the flare risks spinal cord compression. A short antiandrogen course (bicalutamide) given before and during initiation blocks the androgen receptor and covers the flare.
Option A: Option A is incorrect because testosterone initially rises rather than falling within hours.
Option B: Option B is incorrect because finasteride (a 5-alpha-reductase inhibitor) does not adequately block the androgen receptor surge and is not the standard flare-protection strategy.
Option C: Option C is incorrect because the relevant surge is testosterone, not estrogen, and aromatase inhibitors are used in breast cancer.
Option D: Option D is incorrect because corticosteroids do not block the androgen receptor and are not used for flare protection.
10. Enzalutamide, an androgen-receptor inhibitor, is a strong inducer of CYP3A4 (a major drug-metabolizing liver enzyme) and also lowers the seizure threshold. Which statement correctly describes the clinical consequences of these two properties?
A) As a CYP3A4 inhibitor, enzalutamide raises plasma levels of co-administered substrates, and it raises the seizure threshold, making it preferred in epilepsy.
B) Enzalutamide has no clinically relevant drug interactions and no central nervous system effects.
C) As a strong CYP3A4 inducer, enzalutamide lowers plasma concentrations of co-administered substrates such as warfarin (requiring closer INR monitoring), and it is contraindicated or used cautiously in patients with a seizure history because it lowers the seizure threshold.
D) Enzalutamide increases warfarin levels and should be paired with routine vitamin K administration.
E) Enzalutamide induces CYP3A4 but this only affects its own metabolism and never that of other drugs.
ANSWER: C
Rationale:
Enzyme induction increases metabolizing-enzyme expression, accelerating clearance and lowering plasma levels of substrates; as a strong CYP3A4 (and CYP2C9/CYP2C19) inducer, enzalutamide reduces concentrations of many co-administered drugs, including warfarin, so INR (international normalized ratio) monitoring is intensified. It also lowers the seizure threshold and is avoided or used cautiously with a seizure history.
Option A: Option A is incorrect because enzalutamide is an inducer (lowers substrate levels), not an inhibitor, and it lowers rather than raises the seizure threshold.
Option B: Option B is incorrect because it has both significant interactions and central nervous system effects.
Option D: Option D is incorrect because induction lowers warfarin effect rather than increasing it.
Option E: Option E is incorrect because induction broadly affects other CYP3A4 substrates, not only enzalutamide itself.
11. Among the next-generation androgen-receptor inhibitors, darolutamide differs from enzalutamide and apalutamide in ways that matter for drug selection. Which statement most accurately distinguishes darolutamide?
A) Darolutamide has a structurally distinct androgen-receptor-binding scaffold with reduced central nervous system penetration, does not cause seizures at therapeutic doses, and has a more favorable drug-interaction profile (it is not a strong CYP inducer), making it preferred in patients with a seizure history or extensive polypharmacy.
B) Darolutamide has greater central nervous system penetration than enzalutamide and therefore the highest seizure risk of the class.
C) Darolutamide is a CYP17A1 inhibitor that must be co-administered with prednisone.
D) Darolutamide is a GnRH agonist that lowers testosterone by pituitary downregulation.
E) Darolutamide is the only androgen-receptor inhibitor that requires administration on an empty stomach to avoid a 5-fold rise in exposure.
ANSWER: A
Rationale:
Darolutamide's distinct chemical structure limits central nervous system penetration, so it does not lower the seizure threshold the way enzalutamide can, and it lacks strong CYP induction, giving a cleaner interaction profile; these features make it preferred when seizure risk or polypharmacy is a concern.
Option B: Option B is incorrect because darolutamide has reduced, not greater, central nervous system penetration and lower seizure risk.
Option C: Option C describes abiraterone (a CYP17A1 inhibitor requiring prednisone), not darolutamide.
Option D: Option D is incorrect because darolutamide blocks the androgen receptor; it is not a GnRH agonist.
Option E: Option E describes the food effect of abiraterone, not darolutamide.
12. Abiraterone is an irreversible inhibitor of CYP17A1 (17-alpha-hydroxylase/17,20-lyase), the enzyme that synthesizes androgens in the adrenal glands, testes, and tumor. Which pairing correctly states a mandatory co-administration requirement and an administration rule for abiraterone?
A) Co-administer a strong CYP3A4 inducer; take with a high-fat meal to maximize absorption.
B) Co-administer fludrocortisone to add mineralocorticoid; take at bedtime with milk.
C) No corticosteroid is needed; take with grapefruit juice to enhance bioavailability.
D) Co-administer prednisone 5 mg twice daily to replace cortisol and suppress the ACTH-driven mineralocorticoid excess; take on an empty stomach because a high-fat meal can raise abiraterone exposure roughly 5-fold.
E) Co-administer levothyroxine to prevent hypothyroidism; take with the largest meal of the day.
ANSWER: D
Rationale:
CYP17A1 inhibition reduces cortisol synthesis, triggering compensatory ACTH (adrenocorticotropic hormone) elevation that drives accumulation of mineralocorticoid precursors causing hypertension, hypokalemia, and fluid retention; concurrent prednisone 5 mg twice daily replaces cortisol and suppresses ACTH. The standard formulation must be taken on an empty stomach because a high-fat meal raises exposure about 5-fold, producing unpredictable toxicity.
Option A: Option A is incorrect because an inducer would lower abiraterone levels, and high-fat dosing is exactly what to avoid.
Option B: Option B is incorrect because the problem is mineralocorticoid excess (not deficiency), so adding fludrocortisone would worsen it.
Option C: Option C is incorrect because prednisone is mandatory and grapefruit juice (a CYP3A4 inhibitor) is not an appropriate way to alter dosing.
Option E: Option E is incorrect because levothyroxine is unrelated, and abiraterone must be taken fasting, not with a large meal.
13. Tamoxifen is a prodrug requiring conversion by CYP2D6 (a hepatic drug-metabolizing enzyme) to its active metabolite endoxifen. A premenopausal woman on adjuvant tamoxifen for ER-positive breast cancer requests treatment for bothersome hot flashes. Which choice and rationale are correct?
A) Prescribe paroxetine, because it increases endoxifen formation and improves tamoxifen efficacy.
B) Prescribe venlafaxine (or gabapentin or clonidine), and avoid paroxetine and fluoxetine because they are strong CYP2D6 inhibitors that reduce endoxifen levels and may diminish tamoxifen efficacy.
C) Prescribe fluoxetine, because CYP2D6 inhibition has no effect on tamoxifen activity.
D) Discontinue tamoxifen and substitute an aromatase inhibitor, since hot flashes contraindicate all endocrine therapy.
E) Prescribe paroxetine plus a CYP2D6 inducer to keep endoxifen levels neutral.
ANSWER: B
Rationale:
Because endoxifen formation depends on CYP2D6, strong CYP2D6 inhibitors such as paroxetine and fluoxetine reduce endoxifen and may blunt tamoxifen's benefit; venlafaxine, desvenlafaxine, gabapentin, or clonidine are preferred for hot flashes.
Option A: Option A is incorrect because paroxetine inhibits, rather than enhances, the CYP2D6-mediated activation of tamoxifen.
Option C: Option C is incorrect because CYP2D6 inhibition clearly reduces endoxifen and is the basis for avoiding fluoxetine.
Option D: Option D is incorrect because hot flashes are managed pharmacologically and do not contraindicate endocrine therapy; moreover, aromatase inhibitors are ineffective in a premenopausal woman without ovarian suppression.
Option E: Option E is incorrect because combining an inhibitor with an inducer is not a rational or reliable strategy and still risks reduced efficacy.
14. Endocrine therapy for ER-positive breast cancer includes aromatase inhibitors and selective estrogen receptor degraders (SERDs). Which statement correctly distinguishes these mechanisms and their use?
A) Aromatase inhibitors degrade the estrogen receptor, while SERDs block conversion of androgens to estrogen.
B) Aromatase inhibitors are effective in premenopausal women without ovarian suppression, while SERDs work only in men.
C) Elacestrant is an aromatase inhibitor used first-line in all premenopausal patients regardless of mutation status.
D) Fulvestrant is a partial estrogen-receptor agonist identical in mechanism to tamoxifen.
E) Aromatase inhibitors (letrozole, anastrozole, exemestane) block aromatase (CYP19A1) to reduce peripheral estrogen synthesis and are effective only in postmenopausal or ovarian-suppressed women, whereas SERDs such as fulvestrant and oral elacestrant degrade the estrogen receptor, with elacestrant indicated for ESR1-mutant metastatic disease after prior endocrine therapy.
ANSWER: E
Rationale:
Aromatase inhibitors block aromatase (CYP19A1) and lower peripheral estrogen, working only when ovarian estrogen production has ceased (postmenopausal or ovarian-suppressed women); SERDs (fulvestrant, elacestrant) degrade the estrogen receptor itself, and elacestrant is specifically used for ESR1 (estrogen receptor 1 gene)-mutant metastatic disease after endocrine therapy.
Option A: Option A reverses the two mechanisms.
Option B: Option B is incorrect because aromatase inhibitors require the absence of ovarian estrogen, and SERDs are used in women, not only men.
Option C: Option C is incorrect because elacestrant is a SERD targeting ESR1-mutant disease, not a first-line aromatase inhibitor for all premenopausal patients.
Option D: Option D is incorrect because fulvestrant is a pure antagonist and degrader with no agonist activity, unlike the partial-agonist SERM tamoxifen.
15. Cytokine release syndrome (CRS) after CAR-T (chimeric antigen receptor T-cell) infusion is driven largely by interleukin-6 (IL-6). Which statement most accurately reflects the treatment principle for CRS?
A) Corticosteroids are first-line for all grades because they do not affect CAR-T cell expansion.
B) Tocilizumab is ineffective for CRS and is reserved exclusively for neurotoxicity.
C) Tocilizumab, an anti-IL-6-receptor antibody, is the targeted first-line agent for clinically significant CRS, with corticosteroids added for higher-grade or refractory disease; steroids are used after tocilizumab when possible because they can impair CAR-T cell expansion.
D) The first step in CRS is to give a vasopressor and withhold all immunomodulatory therapy indefinitely.
E) CRS is treated with broad-spectrum antifungal therapy, since it represents a fungal infection.
ANSWER: C
Rationale:
Because CRS is largely IL-6-mediated, tocilizumab (anti-IL-6-receptor antibody) is the targeted first-line therapy for clinically significant CRS; corticosteroids are added for higher-grade or refractory cases but are used after tocilizumab when feasible because they can blunt the therapeutic CAR-T expansion.
Option A: Option A is incorrect because corticosteroids are not first-line for all grades and can impair CAR-T expansion.
Option B: Option B is incorrect because tocilizumab is effective and first-line for CRS (it is ICANS where tocilizumab is ineffective).
Option D: Option D is incorrect because supportive vasopressors do not replace targeted anticytokine therapy, and immunomodulation is indicated.
Option E: Option E is incorrect because CRS is a cytokine-driven inflammatory syndrome, not a fungal infection.
16. ICANS (immune effector cell-associated neurotoxicity syndrome) is a distinct CAR-T toxicity graded in part by the ICE (immune effector cell-associated encephalopathy) score. Which statement correctly distinguishes the management of ICANS from that of cytokine release syndrome?
A) ICANS is treated primarily with corticosteroids (dexamethasone), which cross into the central nervous system; tocilizumab is not effective for ICANS and may worsen it because peripheral IL-6-receptor blockade can raise free IL-6 that crosses the blood-brain barrier, and levetiracetam is preferred for seizures.
B) ICANS is treated first-line with tocilizumab, exactly as cytokine release syndrome is.
C) ICANS requires no treatment because the ICE score cannot quantify its severity.
D) ICANS is best treated by escalating the CAR-T cell dose to overcome neurotoxicity.
E) ICANS is managed with phenytoin as the preferred antiseizure agent and with avoidance of all corticosteroids.
ANSWER: A
Rationale:
ICANS responds to corticosteroids (dexamethasone), which penetrate the central nervous system; unlike cytokine release syndrome, it is not effectively treated with tocilizumab, and peripheral IL-6-receptor blockade can raise free IL-6 crossing the blood-brain barrier, potentially worsening neurotoxicity. Levetiracetam is preferred for seizure management.
Option B: Option B is incorrect because tocilizumab is first-line for cytokine release syndrome but not for ICANS.
Option C: Option C is incorrect because ICANS is treatable and the ICE score does grade encephalopathy severity.
Option D: Option D is incorrect and dangerous because raising the CAR-T dose would intensify the immune-mediated injury.
Option E: Option E is incorrect because levetiracetam (not phenytoin) is preferred and corticosteroids are the mainstay rather than something to avoid.
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