Chapter 34 — Anti-Cancer Drugs Part II — Module 2 — Targeted Small Molecule Inhibitors: Conceptual Understanding
1. A patient with BRAF V600E melanoma on single-agent vemurafenib (a BRAF inhibitor) develops a new, rapidly growing keratotic skin nodule. Integrating the mechanism behind this lesion with the appropriate management change, which combined response is correct?
A) The lesion is unrelated to the drug; continue vemurafenib monotherapy and reassure the patient without biopsy
B) The lesion reflects a hypersensitivity reaction; stop vemurafenib permanently and avoid all BRAF-directed therapy
C) The lesion likely reflects paradoxical MAPK pathway activation in BRAF-normal skin cells (cutaneous squamous-cell carcinoma or keratoacanthoma); evaluate or biopsy the lesion and add a MEK inhibitor, which suppresses this paradoxical effect
D) The lesion indicates melanoma progression; immediately switch to cytotoxic chemotherapy and abandon targeted therapy
E) The lesion is a drug-induced infection; treat with systemic antibiotics and continue vemurafenib unchanged
ANSWER: C
Rationale:
This integrates two concepts: why the lesion arises and how management changes. BRAF inhibitor monotherapy paradoxically activates the MAPK growth pathway in cells with normal BRAF, driving cutaneous squamous-cell carcinoma and keratoacanthoma; the correct response is to evaluate or biopsy the lesion and to add a MEK inhibitor, which suppresses the paradoxical activation and reduces these lesions while improving tumor control. The correct choice combines the mechanistic explanation with the management change.
Option A: Option A is incorrect because the lesion is drug-related and a new rapidly growing nodule warrants evaluation rather than reassurance alone.
Option B: Option B is incorrect because this is not a hypersensitivity reaction, and BRAF-directed therapy is continued — typically intensified with a MEK inhibitor — rather than abandoned.
Option D: Option D is incorrect because a new keratotic skin nodule reflects paradoxical activation in normal skin, not melanoma progression, and does not call for switching to cytotoxic chemotherapy.
Option E: Option E is incorrect because the lesion is a neoplastic consequence of paradoxical pathway activation, not an infection, so antibiotics are not the treatment.
2. A woman on ribociclib (a CDK4/6 inhibitor) plus an aromatase inhibitor for breast cancer develops a respiratory infection, and a clinician proposes adding a fluoroquinolone antibiotic. Integrating ribociclib's cardiac property with this prescribing decision, which combined approach is correct?
A) Add the fluoroquinolone freely, since ribociclib has no relevant cardiac interactions
B) Stop ribociclib permanently because any infection during therapy mandates discontinuation
C) Add the fluoroquinolone and double the ribociclib dose to maintain efficacy during the illness
D) Ignore the ECG entirely, since QTc concerns apply only to antiarrhythmic drugs
E) Recognize that both ribociclib and fluoroquinolones prolong the QTc; prefer a non-QTc-prolonging antibiotic, monitor the ECG, and withhold ribociclib if the QTc exceeds the protocol threshold
ANSWER: E
Rationale:
This integrates ribociclib's QTc-prolonging property with a drug-interaction decision. Ribociclib prolongs the QTc and requires ECG monitoring; fluoroquinolones also prolong the QTc, so combining them adds cumulative risk. The correct approach is to choose a non-QTc-prolonging antibiotic where possible, monitor the ECG, and withhold ribociclib if the QTc exceeds the protocol threshold. The correct choice combines avoidance of the additive interaction with the monitoring and threshold actions.
Option A: Option A is incorrect because ribociclib does prolong the QTc and the additive interaction is clinically important.
Option B: Option B is incorrect because an infection does not mandate permanent discontinuation; the issue is managing the additive QTc risk.
Option C: Option C is incorrect because doubling the dose increases cardiac risk and is not how the interaction is managed.
Option D: Option D is incorrect because QTc prolongation is a recognized concern with many drug classes, including antibiotics, not only antiarrhythmics.
3. A patient with borderline (pre-diabetic) fasting glucose is about to start alpelisib (a PI3K-alpha inhibitor) plus fulvestrant for PIK3CA-mutant breast cancer. Integrating the mechanism of alpelisib's signature toxicity with a proactive management plan, which combined approach is most appropriate?
A) Anticipate hyperglycemia from PI3K-alpha-mediated insulin resistance; consider starting metformin pre-emptively, counsel on diet, and monitor fasting glucose before each cycle
B) Anticipate hypoglycemia and provide the patient with glucose tablets, since PI3K-alpha inhibition enhances insulin action
C) Take no metabolic precautions, since alpelisib has no effect on glucose handling
D) Withhold all cancer therapy indefinitely because pre-diabetes is an absolute contraindication to alpelisib
E) Begin high-dose corticosteroids prophylactically to prevent the metabolic effect
ANSWER: A
Rationale:
This integrates mechanism with a proactive plan. Alpelisib blocks PI3K-alpha, the isoform insulin uses for glucose uptake, so hyperglycemia from insulin resistance is its defining and common toxicity; in a patient with borderline glucose, pre-emptive metformin, dietary counseling, and fasting glucose monitoring before each cycle are reasonable proactive measures. The correct choice combines the mechanistic basis with the anticipatory management.
Option B: Option B is incorrect because blocking PI3K-alpha impairs insulin action and raises glucose rather than causing hypoglycemia.
Option C: Option C is incorrect because alpelisib markedly affects glucose handling and precautions are warranted.
Option D: Option D is incorrect because pre-diabetes is not an absolute contraindication; it calls for closer monitoring and proactive management, not withholding therapy.
Option E: Option E is incorrect because corticosteroids would worsen hyperglycemia, not prevent it.
4. A patient on ibrutinib (a first-generation BTK inhibitor) for chronic lymphocytic leukemia is scheduled for a major elective surgery and has also recently developed atrial fibrillation for which anticoagulation is being considered. Integrating ibrutinib's bleeding-related and drug-interaction properties, which combined perioperative and anticoagulation plan is correct?
A) Continue ibrutinib through surgery and start warfarin, since ibrutinib affects neither bleeding nor warfarin levels
B) Continue ibrutinib through surgery and add aspirin for the new atrial fibrillation
C) Stop anticoagulation considerations entirely and proceed to surgery on ibrutinib plus a direct oral anticoagulant at full dose without interruption
D) Hold ibrutinib for several days before surgery because it causes platelet dysfunction; for anticoagulation, avoid warfarin (CYP3A4 interaction raises the INR), prefer a direct oral anticoagulant with awareness of P-glycoprotein-mediated level elevation, and consider switching to a more selective BTK inhibitor
E) Give a higher ibrutinib dose perioperatively to ensure disease control during the surgical period
ANSWER: D
Rationale:
This integrates ibrutinib's platelet effect with its anticoagulant interactions. Ibrutinib causes platelet dysfunction independent of platelet count, so it should be held for several days before major surgery; for the new atrial fibrillation, warfarin is avoided because ibrutinib's CYP3A4 inhibition raises the INR, a direct oral anticoagulant is generally preferred with awareness that ibrutinib's P-glycoprotein inhibition raises its levels, and switching to a more selective second-generation BTK inhibitor reduces both arrhythmia and bleeding risk going forward. The correct choice combines all of these.
Option A: Option A is incorrect because ibrutinib both increases bleeding risk and interacts with warfarin.
Option B: Option B is incorrect because adding aspirin compounds bleeding risk through additive platelet impairment.
Option C: Option C is incorrect because the platelet dysfunction warrants holding the drug perioperatively rather than proceeding uninterrupted.
Option E: Option E is incorrect because raising the dose increases bleeding and arrhythmia risk at the worst possible time.
5. A patient beginning venetoclax (a BCL-2 inhibitor) for acute myeloid leukemia is in the dose ramp-up phase and requires posaconazole, a strong CYP3A4 inhibitor, for antifungal prophylaxis. Integrating the drug interaction with the timing of tumor lysis risk, which combined management is correct?
A) Maintain the full venetoclax dose, withhold hydration, and skip laboratory monitoring during ramp-up
B) Substantially reduce the venetoclax dose because the strong CYP3A4 inhibitor raises its exposure, and because tumor lysis risk is highest during ramp-up maintain aggressive hydration, uric-acid-lowering prophylaxis, and close laboratory monitoring after each increase
C) Increase the venetoclax dose to offset accelerated clearance caused by the antifungal
D) Discontinue venetoclax permanently, since concurrent antifungal use is absolutely contraindicated in all settings
E) Replace venetoclax with a BRAF inhibitor to avoid the interaction
ANSWER: B
Rationale:
This integrates the CYP3A4 interaction with the timing of tumor lysis risk. Because venetoclax is cleared by CYP3A4, posaconazole markedly raises its exposure, so the dose is substantially reduced; and because tumor lysis risk peaks during the ramp-up phase, that period also demands aggressive hydration, uric-acid-lowering prophylaxis, and close post-dose laboratory monitoring. The correct choice combines the interaction-driven dose reduction with the ramp-up safety measures.
Option A: Option A is incorrect and dangerous because it ignores both the raised exposure and the peak tumor lysis risk.
Option C: Option C is incorrect because an inhibitor raises levels rather than accelerating clearance.
Option D: Option D is incorrect because the combination is managed by dose reduction rather than absolute prohibition, since antifungals are frequently needed in these patients.
Option E: Option E is incorrect because a BRAF inhibitor does not treat this disease and switching is not how the interaction is handled.
6. A patient with relapsed chronic lymphocytic leukemia is started on idelalisib (a PI3K-delta inhibitor). Integrating idelalisib's immune-mediated toxicities, its infection risk, and its enzyme-inhibition property, which combined monitoring-and-management plan is correct?
A) No special monitoring is needed, since idelalisib has neither organ toxicity nor infection risk
B) Monitor only blood pressure and give no anti-infective prophylaxis or drug-interaction review
C) Monitor liver enzymes for immune-mediated hepatotoxicity and watch for immune-mediated colitis; provide mandatory Pneumocystis prophylaxis with monitoring for cytomegalovirus reactivation; and review co-medications because idelalisib is a strong CYP3A4 inhibitor that raises levels of CYP3A4-cleared drugs
D) Provide Pneumocystis prophylaxis but disregard liver enzymes and any drug interactions
E) Give the drug with a strong CYP3A4 inhibitor to boost its effect and skip infection prophylaxis
ANSWER: C
Rationale:
This integrates three idelalisib properties. As a PI3K-delta inhibitor it produces immune-mediated hepatotoxicity and colitis requiring liver-enzyme monitoring and vigilance for enterocolitis; it raises opportunistic infection risk, so Pneumocystis prophylaxis is mandatory with cytomegalovirus monitoring; and it is itself a strong CYP3A4 inhibitor, so co-medications cleared by CYP3A4 require review for elevated exposure. The correct choice combines all three.
Option A: Option A is incorrect because idelalisib has substantial organ toxicity and infection risk.
Option B: Option B is incorrect because blood-pressure monitoring alone misses the hepatic, colitic, infectious, and interaction concerns.
Option D: Option D is incorrect because liver-enzyme monitoring and interaction review are also required, not just infection prophylaxis.
Option E: Option E is incorrect because deliberately adding a strong CYP3A4 inhibitor and omitting prophylaxis would increase toxicity and infection risk.
7. A patient on enasidenib (an IDH2 inhibitor) for acute myeloid leukemia presents at week six with new dyspnea, fever, and bilateral pulmonary infiltrates. A covering clinician is about to treat this as community-acquired pneumonia. Integrating the mechanism-based differential with correct management, which combined response is best?
A) It is certainly pneumonia; give antibiotics alone, withhold corticosteroids, and continue enasidenib unchanged without further thought
B) It is certainly heart failure; give high-dose diuresis alone and stop enasidenib permanently
C) It is an allergic reaction; give epinephrine and avoid corticosteroids
D) It is tumor lysis syndrome; give a uric-acid-lowering agent and disregard the pulmonary findings
E) Recognize that differentiation syndrome is high on the differential given the agent and timing; start systemic corticosteroids promptly while evaluating for infection, and continue enasidenib through mild-to-moderate syndrome, holding it only for severe manifestations
ANSWER: E
Rationale:
This integrates the mechanism-driven differential with management. IDH inhibitors force leukemic blasts to mature, and differentiation syndrome — fever, dyspnea, and pulmonary infiltrates within the first weeks — is the characteristic, potentially fatal complication that is frequently misread as pneumonia; the correct response is to start systemic corticosteroids promptly while still evaluating for infection, continuing the drug through mild-to-moderate syndrome and holding it only for severe cases. The correct choice combines recognition with the steroid-based, grade-stratified plan.
Option A: Option A is incorrect because anchoring on pneumonia and withholding corticosteroids risks fatal undertreatment of differentiation syndrome.
Option B: Option B is incorrect because the picture is not simple heart failure and diuresis alone with permanent discontinuation is not the management.
Option C: Option C is incorrect because this is an inflammatory consequence of forced maturation, not an allergic reaction, and corticosteroids are essential.
Option D: Option D is incorrect because the pulmonary infiltrates point to differentiation syndrome rather than tumor lysis, which would not be addressed by a uric-acid-lowering agent.
8. A patient starting bortezomib (a proteasome inhibitor) for multiple myeloma will also receive an azole antifungal that strongly inhibits CYP3A4. Integrating bortezomib's metabolism, its route-dependent neuropathy risk, and the class infection-prophylaxis requirement, which combined plan is correct?
A) Recognize that the strong CYP3A4 inhibitor raises bortezomib exposure, so monitor for toxicity or prefer an alternative antifungal; give bortezomib subcutaneously to reduce peripheral neuropathy; and provide antiviral prophylaxis against herpes zoster reactivation
B) Give bortezomib intravenously at a higher dose, ignore the antifungal interaction, and provide no antiviral prophylaxis
C) Take no interaction precautions, since bortezomib is not metabolized by CYP3A4
D) Provide antiviral prophylaxis but choose the intravenous route specifically to maximize neuropathy for therapeutic effect
E) Withhold all antifungal therapy permanently and give bortezomib by mouth
ANSWER: A
Rationale:
This integrates three considerations. Bortezomib is metabolized by CYP3A4, so a strong inhibitor raises its exposure and prompts monitoring or an alternative antifungal; the subcutaneous route markedly lowers peripheral neuropathy at equivalent exposure and is preferred; and proteasome inhibitors as a class require antiviral prophylaxis against herpes zoster reactivation. The correct choice combines the interaction awareness, the route choice, and the antiviral prophylaxis.
Option B: Option B is incorrect because raising the intravenous dose worsens neuropathy and ignores both the interaction and the zoster risk.
Option C: Option C is incorrect because bortezomib is indeed a CYP3A4 substrate, so the interaction matters.
Option D: Option D is incorrect because the intravenous route increases neuropathy, which is undesirable rather than therapeutic.
Option E: Option E is incorrect because antifungal prophylaxis is often needed and bortezomib has no oral formulation; the oral proteasome inhibitor is a different agent.
9. A patient with relapsed multiple myeloma after bortezomib has limiting peripheral neuropathy, and carfilzomib (a second-generation proteasome inhibitor) is being considered for deeper response. Integrating the rationale for switching with carfilzomib's distinguishing safety considerations, which combined assessment is correct?
A) Carfilzomib is a poor choice after bortezomib because it causes even more peripheral neuropathy than bortezomib
B) Carfilzomib requires no baseline assessment and may be used regardless of cardiac history
C) Carfilzomib should be avoided in all patients because it offers no efficacy advantage over bortezomib
D) Carfilzomib can provide deeper responses after bortezomib and tends to cause less peripheral neuropathy, but because its distinguishing toxicity is cardiovascular, perform baseline cardiac assessment, exclude patients with advanced heart failure, and use careful hydration around infusions
E) Carfilzomib is interchangeable with bortezomib in route and toxicity, so the switch changes nothing clinically
ANSWER: D
Rationale:
This integrates the reason to switch with carfilzomib's safety profile. Carfilzomib can yield deeper responses in relapsed disease and, by its mechanism of irreversible inhibition, tends to cause less peripheral neuropathy than bortezomib — favorable for a patient limited by neuropathy — but its distinguishing toxicity is cardiovascular, so baseline cardiac assessment, exclusion of advanced (New York Heart Association class III or IV) heart failure, and careful hydration around infusions are required. The correct choice combines the efficacy and neuropathy rationale with the cardiac safeguards.
Option A: Option A is incorrect because carfilzomib causes less, not more, neuropathy than bortezomib.
Option B: Option B is incorrect because baseline cardiac assessment is specifically required and cardiac history matters.
Option C: Option C is incorrect because carfilzomib does offer an efficacy advantage in the relapsed or refractory setting.
Option E: Option E is incorrect because the two agents differ in route, neuropathy profile, and cardiovascular risk, so the switch is clinically meaningful.
10. A patient with newly diagnosed multiple myeloma, reduced creatinine clearance (the estimate of renal filtration), and a prior deep vein thrombosis is to begin lenalidomide (an immunomodulatory drug) with high-dose dexamethasone. Integrating renal handling, thrombosis risk, and the class safety program, which combined plan is correct?
A) Use a standard lenalidomide dose regardless of renal function, give aspirin only, and skip the safety-program requirements
B) Reduce the lenalidomide dose for the reduced creatinine clearance because it is renally eliminated; provide therapeutic anticoagulation rather than aspirin because high-dose dexamethasone plus prior venous thromboembolism is high-risk; and enroll the patient in the required risk-management (REMS) program with contraception and pregnancy-testing compliance as applicable
C) Increase the lenalidomide dose because renal impairment lowers its levels, and provide no thromboprophylaxis
D) Avoid lenalidomide entirely because renal impairment is an absolute contraindication at any clearance
E) Give thalidomide-style renal dose reduction, since lenalidomide and thalidomide are handled identically by the kidney
ANSWER: B
Rationale:
This integrates three lenalidomide considerations. Lenalidomide is predominantly renally eliminated, so the dose is reduced as creatinine clearance falls; the combination of high-dose dexamethasone with a prior venous thromboembolism is high-risk, calling for therapeutic anticoagulation rather than aspirin; and all immunomodulatory drugs require enrollment in a risk-management program with contraception and pregnancy-testing requirements as applicable. The correct choice combines all three.
Option A: Option A is incorrect because it ignores renal dosing, undertreats a high thrombosis risk, and omits the mandatory safety program.
Option C: Option C is incorrect because renal impairment raises, not lowers, lenalidomide exposure, so the dose is reduced, and thromboprophylaxis is required.
Option D: Option D is incorrect because renal impairment calls for dose reduction (and avoidance only below a severe threshold without dialysis), not blanket avoidance at any clearance.
Option E: Option E is incorrect because thalidomide is largely non-renally cleared, so the two drugs are not handled identically by the kidney.
11. A patient with ovarian cancer who responded to platinum chemotherapy is being considered for maintenance with a PARP inhibitor, and niraparib is the agent under discussion. Integrating the mechanism that selects appropriate patients with the agent-specific monitoring, which combined plan is correct?
A) PARP inhibitors work independently of repair status, so no molecular testing is needed, and niraparib requires no special blood-count monitoring
B) Confirm that the tumor has fully intact homologous-recombination repair, since intact repair predicts PARP inhibitor benefit, and monitor only liver enzymes with niraparib
C) Avoid molecular testing because BRCA and homologous-recombination status has no bearing on PARP inhibitor selection, and give niraparib without monitoring
D) Choose niraparib specifically because it is metabolized by CYP3A4, making drug interactions the only relevant consideration
E) Use BRCA and homologous-recombination-deficiency testing to identify tumors that lack back-up repair (the synthetic-lethality basis of benefit), and recognize that niraparib in particular requires weekly blood-count monitoring early in therapy because of its high thrombocytopenia rate
ANSWER: E
Rationale:
This integrates patient selection with agent-specific monitoring. PARP inhibitors exploit synthetic lethality: they selectively kill tumors that have lost their back-up homologous-recombination repair (BRCA-mutant or otherwise homologous-recombination-deficient), so BRCA and homologous-recombination-deficiency testing guides selection; and among PARP inhibitors, niraparib is distinguished by a high rate of thrombocytopenia, prompting weekly blood-count monitoring early in therapy. The correct choice combines the selection mechanism with the niraparib monitoring.
Option A: Option A is incorrect because PARP inhibitor benefit depends on repair status and niraparib does require blood-count monitoring.
Option B: Option B is incorrect because it inverts the mechanism — deficient, not intact, repair predicts benefit.
Option C: Option C is incorrect because BRCA and homologous-recombination status is central to selection.
Option D: Option D is incorrect because niraparib is metabolized chiefly by carboxylesterases rather than CYP3A4, and interactions are not the only relevant consideration; thrombocytopenia monitoring is key.
12. Three agents in this module can each raise blood glucose, but by distinct mechanisms: alpelisib (a PI3K-alpha inhibitor), everolimus (an mTOR inhibitor), and dexamethasone (a corticosteroid often combined with these regimens). Integrating these mechanisms, which statement correctly distinguishes how each produces hyperglycemia?
A) Alpelisib causes insulin resistance by blocking PI3K-alpha-mediated insulin signaling; everolimus impairs beta-cell compensation and adds insulin resistance through mTOR inhibition; and dexamethasone produces corticosteroid-associated hyperglycemia, often in a meal-related pattern
B) All three raise glucose by the identical mechanism of direct pancreatic islet destruction
C) None of the three affects glucose; the hyperglycemia is incidental and unrelated to the drugs
D) Alpelisib and everolimus lower glucose, while only dexamethasone raises it
E) Dexamethasone lowers glucose, offsetting the hyperglycemia caused by the other two
ANSWER: A
Rationale:
This integrates three separate mechanisms of drug-induced hyperglycemia. Alpelisib blocks PI3K-alpha, the isoform insulin uses for glucose uptake, producing insulin resistance; everolimus, through mTOR inhibition, impairs beta-cell compensation and contributes to insulin resistance; and dexamethasone causes corticosteroid-associated hyperglycemia that often follows a meal-related pattern and may call for mealtime short-acting insulin. The correct choice distinguishes all three mechanisms.
Option B: Option B is incorrect because the three act by different mechanisms, none of which is direct islet destruction.
Option C: Option C is incorrect because each drug genuinely affects glucose handling.
Option D: Option D is incorrect because alpelisib and everolimus raise, not lower, glucose.
Option E: Option E is incorrect because dexamethasone raises glucose rather than offsetting hyperglycemia.
13. Several agents in this module require pre-operative holding for different mechanistic reasons. A clinician is planning major surgery for patients on, respectively, a BTK inhibitor, an immunomodulatory drug, and a PARP inhibitor. Integrating the distinct reasons each is held, which statement is correct?
A) None of these agents needs to be held before surgery, since none affects bleeding, clotting, or healing
B) All three are held for the identical reason of QTc prolongation
C) The BTK inhibitor is held because it causes platelet dysfunction and bleeding risk; the immunomodulatory drug is held because immobility compounds its venous thromboembolism risk; and the PARP inhibitor is held because impaired DNA repair can affect surgical wound healing
D) Only the PARP inhibitor must be held, and solely because of QTc prolongation
E) All three are held because they are proteasome inhibitors requiring cardiac clearance
ANSWER: C
Rationale:
This integrates three distinct perioperative rationales. A BTK inhibitor (such as ibrutinib) is held because it causes platelet dysfunction and bleeding risk; an immunomodulatory drug is held because surgical immobility compounds its venous thromboembolism risk; and a PARP inhibitor is held because its interference with DNA repair can impair surgical wound healing. The correct choice attributes each hold to its correct mechanism.
Option A: Option A is incorrect because each of these agents has a specific perioperative concern.
Option B: Option B is incorrect because the three are held for different reasons, not a shared QTc effect.
Option D: Option D is incorrect because all three require perioperative attention, and the PARP inhibitor's reason is impaired DNA repair and wound healing, not QTc.
Option E: Option E is incorrect because these agents are not all proteasome inhibitors and the holds are not for a common cardiac clearance.
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