A 70-year-old man with metastatic castration-resistant prostate cancer has rising PSA despite enzalutamide therapy. Imaging shows new bone metastases but no visceral disease. He has a history of well-controlled seizures on levetiracetam, type 2 diabetes on metformin, and stage 3 chronic kidney disease (eGFR 42 mL/min). Genetic testing shows BRCA2 germline mutation and homologous recombination deficiency. The oncologist considers four treatment options: docetaxel chemotherapy, radium-223, olaparib, or lutetium-177-PSMA. Synthesize the clinical data and evaluate the optimal treatment considering efficacy, mechanism, and patient-specific factors.
Q2
A 38-year-old woman with metastatic colon cancer has progressed through multiple lines of therapy including FOLFOX, FOLFIRI, and bevacizumab. Molecular testing reveals microsatellite instability-high (MSI-H) status and BRAF V600E mutation. She has excellent performance status but developed severe neuropathy from prior oxaliplatin. Her oncologist is considering three options: regorafenib, pembrolizumab, or encorafenib plus cetuximab. Evaluate the tumor biology and synthesize the optimal treatment strategy considering efficacy and toxicity.
Q3
A 52-year-old woman with newly diagnosed acute promyelocytic leukemia (APL) presents with WBC count of 45 × 10^9/L, pancytopenia, and coagulopathy (PT 18 sec, PTT 42 sec, fibrinogen 95 mg/dL, D-dimer elevated). She is started on all-trans retinoic acid (ATRA) and arsenic trioxide. On day 7, she develops fever, dyspnea, hypotension, pulmonary infiltrates on chest X-ray, and weight gain of 5 kg. Her WBC is now 78 × 10^9/L. Evaluate the pathophysiology and synthesize the optimal management strategy.
Q4
A 67-year-old man with chronic lymphocytic leukemia is being considered for treatment with ibrutinib. His medications include warfarin for atrial fibrillation (INR therapeutic at 2.5), lisinopril, and metformin. He has normal renal and hepatic function. His CHA2DS2-VASc score is 4. Analyze the drug interactions and evaluate the safest anticoagulation strategy.
Q5
A 42-year-old man with metastatic melanoma is started on ipilimumab and nivolumab combination immunotherapy. After the second dose, he develops severe watery diarrhea (8-10 stools/day), abdominal cramping, and rectal bleeding. Colonoscopy shows diffuse colitis with ulcerations. Laboratory tests show normal electrolytes and kidney function. Stool studies for infectious causes are negative. Analyze the underlying mechanism and determine appropriate management.
Q6
A 58-year-old woman with metastatic HER2-positive breast cancer has been on trastuzumab and pertuzumab for 18 months with good disease control. She now presents with progressive dyspnea on exertion. Echocardiography shows left ventricular ejection fraction of 42% (baseline 65%). She has no history of cardiac disease and previous anthracycline exposure was 4 years ago. Analyze the pathophysiology and determine the management approach.
Q7
A 48-year-old man receiving cisplatin-based chemotherapy for testicular cancer develops tinnitus and difficulty hearing conversations. Audiometry confirms bilateral high-frequency sensorineural hearing loss. He has completed 2 of 4 planned cycles. His tumor markers are decreasing appropriately. Apply the most appropriate modification to his treatment regimen.
Q8
A 55-year-old woman with acute myeloid leukemia is being treated with cytarabine and idarubicin. On day 5 of therapy, laboratory results show: WBC 0.8 × 10^9/L, hemoglobin 7.2 g/dL, platelets 18 × 10^9/L, potassium 6.8 mEq/L, phosphate 6.2 mg/dL, uric acid 12.5 mg/dL, creatinine 2.8 mg/dL (baseline 0.9). Apply the immediate management for this patient's condition.
Q9
A 62-year-old man with metastatic colorectal cancer is started on FOLFOX chemotherapy (5-fluorouracil, leucovorin, and oxaliplatin). After the first cycle, he develops numbness and tingling in his fingers that worsens when he drinks cold beverages. Apply the appropriate management strategy for this patient's symptoms.
Q10
A 45-year-old woman with metastatic breast cancer presents with severe nausea and vomiting 24 hours after receiving her first cycle of doxorubicin and cyclophosphamide chemotherapy. She has tried ondansetron without relief. Her ECG shows QTc of 380 ms, and she has no history of cardiac disease. Apply the appropriate antiemetic management for this patient.
Anti-neoplastic drugs US Medical PG Practice Questions and MCQs
Question 1: A 70-year-old man with metastatic castration-resistant prostate cancer has rising PSA despite enzalutamide therapy. Imaging shows new bone metastases but no visceral disease. He has a history of well-controlled seizures on levetiracetam, type 2 diabetes on metformin, and stage 3 chronic kidney disease (eGFR 42 mL/min). Genetic testing shows BRCA2 germline mutation and homologous recombination deficiency. The oncologist considers four treatment options: docetaxel chemotherapy, radium-223, olaparib, or lutetium-177-PSMA. Synthesize the clinical data and evaluate the optimal treatment considering efficacy, mechanism, and patient-specific factors.
A. Start olaparib targeting the BRCA2 mutation and HRD pathway (Correct Answer)
B. Use radium-223 for symptomatic bone metastases without visceral disease
C. Administer lutetium-177-PSMA therapy if PSMA-PET scan is positive
D. Continue enzalutamide and add abiraterone for combination androgen blockade
E. Initiate docetaxel chemotherapy given proven survival benefit in this setting
Explanation: ***Start olaparib targeting the BRCA2 mutation and HRD pathway***
- **Olaparib** is a **PARP inhibitor** that utilizes the principle of **synthetic lethality** in cells with **BRCA2 mutations** or other **homologous recombination deficiency (HRD)**.
- According to the **PROfound trial**, olaparib significantly improves **radiographic progression-free survival** in patients with mCRPC who have progressed on prior hormonal therapy and harbor BRCA mutations.
*Use radium-223 for symptomatic bone metastases without visceral disease*
- While this patient has bone metastases, **Radium-223** is primarily indicated for **symptomatic** bone metastases to improve overall survival and delay skeletal events.
- It does not specifically target the underlying **molecular drivers** (like BRCA2) and is less prioritized than targeted therapy in an asymptomatic rising PSA clinical setting.
*Administer lutetium-177-PSMA therapy if PSMA-PET scan is positive*
- **Lutetium-177-PSMA** is typically indicated for patients who have already progressed on at least one **taxane-based chemotherapy** and an **androgen receptor pathway inhibitor (ARPI)**.
- Although effective, it is currently positioned later in the treatment sequence compared to **PARP inhibitors** for patients with specific **germline mutations**.
*Continue enzalutamide and add abiraterone for combination androgen blockade*
- Switching from one **ARPI** (enzalutamide) to another (abiraterone) generally yields poor results due to **cross-resistance** mechanisms within the androgen receptor.
- Combining these agents provides minimal clinical benefit and increases **toxicity**, such as the risk of hepatotoxicity and mineralocorticoid excess.
*Initiate docetaxel chemotherapy given proven survival benefit in this setting*
- **Docetaxel** is a viable option for mCRPC, but given the patient's age and **CKD comorbidities**, a targeted oral agent like olaparib is often preferred first for **BRCA-mutant** cases.
- Precision medicine dictates using **biomarker-driven therapies** (PARP inhibitors) before proceeding to more cytotoxic, systemic **chemotherapy** when a targetable mutation is present.
Question 2: A 38-year-old woman with metastatic colon cancer has progressed through multiple lines of therapy including FOLFOX, FOLFIRI, and bevacizumab. Molecular testing reveals microsatellite instability-high (MSI-H) status and BRAF V600E mutation. She has excellent performance status but developed severe neuropathy from prior oxaliplatin. Her oncologist is considering three options: regorafenib, pembrolizumab, or encorafenib plus cetuximab. Evaluate the tumor biology and synthesize the optimal treatment strategy considering efficacy and toxicity.
A. Resume FOLFIRI without oxaliplatin to avoid worsening neuropathy
B. Start regorafenib as it is approved for refractory metastatic colorectal cancer
C. Initiate pembrolizumab based on MSI-H status regardless of BRAF mutation (Correct Answer)
D. Use encorafenib plus cetuximab targeting the BRAF V600E mutation
E. Combine pembrolizumab with encorafenib for dual mechanism targeting
Explanation: ***Initiate pembrolizumab based on MSI-H status regardless of BRAF mutation***
- **Microsatellite Instability-High (MSI-H)** status is a superior predictive biomarker for **immune checkpoint inhibitors**, offering high objective response rates and durable survival compared to other salvage therapies.
- **Pembrolizumab** is the preferred treatment in MSI-H metastatic colorectal cancer due to its high therapeutic index and favorable toxicity profile compared to the severe neuropathy risk and low efficacy of further chemotherapy.
*Resume FOLFIRI without oxaliplatin to avoid worsening neuropathy*
- While avoiding **oxaliplatin** prevents worsening of **peripheral neuropathy**, the patient has already progressed on **FOLFIRI**, indicating acquired resistance to this regimen.
- Standard cytotoxic chemotherapy provides significantly lower survival benefits in the **MSI-H/BRAF mutant** setting compared to targeted immunotherapy.
*Start regorafenib as it is approved for refractory metastatic colorectal cancer*
- **Regorafenib** is typically reserved as a last-line therapy due to its modest survival benefit and a high incidence of **hand-foot skin reaction** and fatigue.
- It is less effective than **pembrolizumab** for **MSI-H** tumors and does not specifically address the high tumor mutational burden characteristic of this patient's cancer.
*Use encorafenib plus cetuximab targeting the BRAF V600E mutation*
- Although this combination is effective for **BRAF V600E** mutations, clinical data suggests that **immunotherapy** (MSI-H targeted) takes precedence over BRAF-targeted therapy in patients who are both MSI-H and BRAF mutant.
- The **BEACON trial** established this regimen, but current guidelines prioritize **immune checkpoint inhibitors** for MSI-H status before utilizing BRAF inhibitors.
*Combine pembrolizumab with encorafenib for dual mechanism targeting*
- While theoretically plausible, this combination is not the current **standard of care** and lacks robust clinical evidence for routine use in the salvage setting.
- Sequential mono-immunotherapy is preferred to avoid potential **cumulative toxicities** from combining a BRAF inhibitor with a PD-1 inhibitor without proven additive benefits.
Question 3: A 52-year-old woman with newly diagnosed acute promyelocytic leukemia (APL) presents with WBC count of 45 × 10^9/L, pancytopenia, and coagulopathy (PT 18 sec, PTT 42 sec, fibrinogen 95 mg/dL, D-dimer elevated). She is started on all-trans retinoic acid (ATRA) and arsenic trioxide. On day 7, she develops fever, dyspnea, hypotension, pulmonary infiltrates on chest X-ray, and weight gain of 5 kg. Her WBC is now 78 × 10^9/L. Evaluate the pathophysiology and synthesize the optimal management strategy.
A. Diagnose drug-induced pneumonitis, discontinue arsenic permanently and continue ATRA
B. Diagnose pneumonia, start broad-spectrum antibiotics and continue ATRA/arsenic
C. Diagnose differentiation syndrome, start dexamethasone 10 mg IV q12h, temporarily hold ATRA (Correct Answer)
D. Diagnose tumor lysis syndrome, start rasburicase and discontinue both agents
E. Diagnose pulmonary leukostasis, start leukapheresis and hydroxyurea
Explanation: ***Diagnose differentiation syndrome, start dexamethasone 10 mg IV q12h, temporarily hold ATRA***
- The patient presents with classic signs of **differentiation syndrome** (formerly ATRA syndrome), characterized by fever, dyspnea, **pulmonary infiltrates**, hypotension, and weight gain due to **capillary leak**.
- Management requires immediate administration of **high-dose dexamethasone** and temporarily holding the differentiating agents (ATRA/Arsenic) until symptoms stabilize.
*Diagnose drug-induced pneumonitis, discontinue arsenic permanently and continue ATRA*
- Drug-induced pneumonitis is a diagnosis of exclusion and does not account for the **hyperleukocytosis** and multi-organ involvement (weight gain/hypotension) seen here.
- Discontinuing arsenic while continuing **ATRA** is incorrect, as ATRA is the primary driver of the **cytokine release** causing the syndrome.
*Diagnose pneumonia, start broad-spectrum antibiotics and continue ATRA/arsenic*
- While fever and infiltrates can mimic pneumonia, the rapid **weight gain** and association with **ATRA/Arsenic therapy** point specifically to differentiation syndrome.
- Delaying steroids to wait for antibiotic response can be fatal, as this is an **inflammatory emergency** rather than a primary infection.
*Diagnose tumor lysis syndrome, start rasburicase and discontinue both agents*
- **Tumor lysis syndrome (TLS)** typically presents with metabolic derangements like **hyperuricemia** and hyperkalemia, which are not the primary features described.
- While TLS can occur in APL, it does not explain the **pulmonary edema** and capillary leak symptoms as effectively as differentiation syndrome does.
*Diagnose pulmonary leukostasis, start leukapheresis and hydroxyurea*
- Although the WBC count is elevated, **leukapheresis** is generally contraindicated in APL because it can worsen the underlying **coagulopathy** (DIC).
- The clinical picture of weight gain and response to differentiation therapy is pathognomonic for **differentiation syndrome**, making steroids the first-line treatment over cytoreduction.
Question 4: A 67-year-old man with chronic lymphocytic leukemia is being considered for treatment with ibrutinib. His medications include warfarin for atrial fibrillation (INR therapeutic at 2.5), lisinopril, and metformin. He has normal renal and hepatic function. His CHA2DS2-VASc score is 4. Analyze the drug interactions and evaluate the safest anticoagulation strategy.
A. Continue warfarin and start ibrutinib with weekly INR monitoring
B. Switch to apixaban and start ibrutinib after 48-hour washout period
C. Discontinue anticoagulation and start ibrutinib with aspirin prophylaxis
D. Continue warfarin, use alternative BTK inhibitor acalabrutinib instead (Correct Answer)
E. Switch to low molecular weight heparin and proceed with ibrutinib
Explanation: ***Continue warfarin, use alternative BTK inhibitor acalabrutinib instead***
- **Ibrutinib** carries a significant risk of bleeding and **atrial fibrillation**; using it with **warfarin** is generally contraindicated or highly cautioned due to major hemorrhagic risks.
- **Acalabrutinib** is a more selective, second-generation **BTK inhibitor** with lower rates of bleeding and cardiovascular toxicity, making it a safer profile for patients requiring chronic **anticoagulation**.
*Continue warfarin and start ibrutinib with weekly INR monitoring*
- **Ibrutinib** inhibits **platelet aggregation** via off-target effects on TEC-family kinases, which adds significantly to the bleeding risk of **warfarin** regardless of INR levels.
- Clinical guidelines specifically advise against the co-administration of **ibrutinib** and **vitamin K antagonists** due to the high incidence of major hemorrhage.
*Switch to apixaban and start ibrutinib after 48-hour washout period*
- Both **ibrutinib** and **apixaban** are metabolized by **CYP3A4**, leading to potential drug-drug interactions that can unpredictably alter anticoagulant levels.
- While **DOACs** are sometimes used with BTK inhibitors, fixed-dose anticoagulation with **ibrutinib** still poses a higher bleeding risk than choosing a more selective agent like **acalabrutinib**.
*Discontinue anticoagulation and start ibrutinib with aspirin prophylaxis*
- A **CHA2DS2-VASc score of 4** indicates a high risk of thromboembolic stroke, and **aspirin** is insufficient for stroke prophylaxis in **atrial fibrillation**.
- Discontinuing effective **anticoagulation** would place the patient at an unacceptable risk for a **cerebrovascular accident**.
*Switch to low molecular weight heparin and proceed with ibrutinib*
- **Low molecular weight heparin** does not mitigate the intrinsic **platelet dysfunction** caused by **ibrutinib**, and long-term use is burdensome for chronic CLL management.
- The primary issue is the **pharmacodynamic interaction** between **ibrutinib** and any systemic anticoagulant; hence, changing the BTK inhibitor is the more appropriate strategy.
Question 5: A 42-year-old man with metastatic melanoma is started on ipilimumab and nivolumab combination immunotherapy. After the second dose, he develops severe watery diarrhea (8-10 stools/day), abdominal cramping, and rectal bleeding. Colonoscopy shows diffuse colitis with ulcerations. Laboratory tests show normal electrolytes and kidney function. Stool studies for infectious causes are negative. Analyze the underlying mechanism and determine appropriate management.
A. Continue immunotherapy and start sulfasalazine for inflammatory bowel disease
B. Hold immunotherapy, start high-dose methylprednisolone, consider infliximab if no improvement in 3 days (Correct Answer)
C. Discontinue nivolumab only and continue ipilimumab monotherapy with loperamide
D. Stop both agents permanently and start vedolizumab for immune-related colitis
E. Continue both agents at reduced doses with budesonide for colitis management
Explanation: ***Hold immunotherapy, start high-dose methylprednisolone, consider infliximab if no improvement in 3 days***
- This patient presents with Grade 3/4 **immune-related adverse events (irAEs)**, specifically severe colitis characterized by >7 stools/day and rectal bleeding requiring immediate systemic **corticosteroids**.
- Protocol dictates holding the **checkpoint inhibitors** and escalating to biologics like **infliximab** or vedolizumab if there is no significant clinical improvement within **48-72 hours**.
*Continue immunotherapy and start sulfasalazine for inflammatory bowel disease*
- Continuing therapy in the setting of severe **colitis** is contraindicated due to the high risk of **bowel perforation** or death.
- **Sulfasalazine** is ineffective for acute, high-grade immune-mediated toxicity, which requires potent T-cell suppression via **systemic steroids**.
*Discontinue nivolumab only and continue ipilimumab monotherapy with loperamide*
- **Ipilimumab (CTLA-4 inhibitor)** is actually more strongly associated with severe colitis than **Nivolumab (PD-1 inhibitor)**; continuing it would worsen the inflammatory response.
- **Loperamide** is used for mild (Grade 1) diarrhea but is dangerous in severe colitis as it can mask symptoms or trigger **toxic megacolon**.
*Stop both agents permanently and start vedolizumab for immune-related colitis*
- While both agents are held, permanent discontinuation might not be decided immediately; however, **first-line therapy** for high-grade colitis is **methylprednisolone**, not vedolizumab.
- **Vedolizumab** is generally reserved for patients who are **steroid-refractory** or have contraindications to TNF-alpha inhibitors like infliximab.
*Continue both agents at reduced doses with budesonide for colitis management*
- Dose reduction is not a standard strategy for managing severe **checkpoint inhibitor toxicity**; treatment must be held until symptoms resolve to Grade 1 or less.
- **Budesonide** is a locally acting steroid appropriate only for **Grade 1 or mild Grade 2** diarrhea, not for severe colitis with ulcerations seen on colonoscopy.
Question 6: A 58-year-old woman with metastatic HER2-positive breast cancer has been on trastuzumab and pertuzumab for 18 months with good disease control. She now presents with progressive dyspnea on exertion. Echocardiography shows left ventricular ejection fraction of 42% (baseline 65%). She has no history of cardiac disease and previous anthracycline exposure was 4 years ago. Analyze the pathophysiology and determine the management approach.
A. Permanently discontinue both HER2-targeted agents and start capecitabine
B. Hold trastuzumab/pertuzumab, start ACE inhibitor and beta-blocker, reassess in 4 weeks (Correct Answer)
C. Continue current therapy and add spironolactone for heart failure management
D. Switch to ado-trastuzumab emtansine (T-DM1) immediately
E. Reduce trastuzumab dose by 50% and continue pertuzumab at full dose
Explanation: ***Hold trastuzumab/pertuzumab, start ACE inhibitor and beta-blocker, reassess in 4 weeks***
- **Trastuzumab-induced cardiotoxicity** (Type II) involves reversible **myocardial stunning** rather than cell death, necessitating a temporary pause when the **LVEF** drops significantly.
- Standard management for symptomatic **heart failure** or an LVEF <40-45% includes initiating **ACE inhibitors** or **beta-blockers** and re-evaluating cardiac function before resuming therapy.
*Permanently discontinue both HER2-targeted agents and start capecitabine*
- Permanent discontinuation is premature because **HER2-targeted cardiotoxicity** is typically **reversible** and not dose-dependent like anthracyclines.
- **Capecitabine** is a later-line treatment and does not address the patient's current **cardiac dysfunction** or utilize her effective current regimen.
*Continue current therapy and add spironolactone for heart failure management*
- Continuing HER2 inhibitors in the setting of **symptomatic heart failure** or a substantial LVEF drop (from 65% to 42%) risks further cardiac decompensation.
- Clinical guidelines mandate **holding the offending agent** until cardiac function stabilizes or improves during medical management.
*Switch to ado-trastuzumab emtansine (T-DM1) immediately*
- **T-DM1** is also associated with **cardiotoxicity** and is not indicated as a solution for managing an acute decline in ejection fraction.
- Switching agents ignores the underlying **pathophysiology** of HER2-related cardiac injury which requires a treatment break and medical support.
*Reduce trastuzumab dose by 50% and continue pertuzumab at full dose*
- Dose reduction is not a validated strategy for managing **trastuzumab-induced cardiomyopathy**; the drug must be held entirely.
- Continuing **pertuzumab** alone is insufficient for both oncologic control and preventing further **cardiac strain** in the acute setting.
Question 7: A 48-year-old man receiving cisplatin-based chemotherapy for testicular cancer develops tinnitus and difficulty hearing conversations. Audiometry confirms bilateral high-frequency sensorineural hearing loss. He has completed 2 of 4 planned cycles. His tumor markers are decreasing appropriately. Apply the most appropriate modification to his treatment regimen.
A. Continue cisplatin at current dose with hearing monitoring
B. Switch to carboplatin for remaining cycles (Correct Answer)
C. Reduce cisplatin dose by 50% and add amifostine
D. Discontinue platinum therapy and switch to etoposide monotherapy
E. Continue cisplatin and add vitamin E supplementation
Explanation: ***Switch to carboplatin for remaining cycles***
- **Cisplatin** causes dose-dependent, irreversible **ototoxicity** by damaging hair cells in the **organ of Corti**, typically presenting as high-frequency hearing loss.
- **Carboplatin** is significantly less ototoxic than cisplatin and serves as an effective alternative to maintain therapeutic efficacy in **testicular cancer** while preventing permanent deafness.
*Continue cisplatin at current dose with hearing monitoring*
- Continuing the drug would result in progressive and **permanent hearing loss**, as cisplatin toxicity is cumulative and the patient is already symptomatic.
- **Audiometry** changes in the presence of tinnitus indicate advanced damage that requires immediate cessation of the causative agent.
*Reduce cisplatin dose by 50% and add amifostine*
- Dose reduction may compromise the **curative potential** of the chemotherapy regimen for germ cell tumors.
- **Amifostine** is primarily used to reduce **nephrotoxicity**, and its efficacy in preventing or reversing established cisplatin-induced **ototoxicity** is not well-supported.
*Discontinue platinum therapy and switch to etoposide monotherapy*
- **Platinum agents** are the cornerstone of curative treatment for testicular cancer; discontinuing them entirely would significantly increase the risk of disease relapse.
- **Etoposide monotherapy** is insufficient for the management of aggressive germ cell tumors which require a combination approach.
*Continue cisplatin and add vitamin E supplementation*
- There is no clinical evidence that **vitamin E** or other antioxidants can reverse or effectively shield the cochlea from **cisplatin-induced damage** once symptoms have manifested.
- Delaying the switch to a less toxic agent like carboplatin places the patient at risk for profound, debilitating **sensorineural hearing loss**.
Question 8: A 55-year-old woman with acute myeloid leukemia is being treated with cytarabine and idarubicin. On day 5 of therapy, laboratory results show: WBC 0.8 × 10^9/L, hemoglobin 7.2 g/dL, platelets 18 × 10^9/L, potassium 6.8 mEq/L, phosphate 6.2 mg/dL, uric acid 12.5 mg/dL, creatinine 2.8 mg/dL (baseline 0.9). Apply the immediate management for this patient's condition.
A. Administer allopurinol and increase IV fluid rate to 200 mL/hour
B. Start rasburicase, aggressive hydration, and electrolyte management (Correct Answer)
C. Begin hemodialysis and discontinue chemotherapy permanently
D. Give calcium gluconate and sodium polystyrene sulfonate only
E. Administer febuxostat and continue current chemotherapy regimen
Explanation: ***Start rasburicase, aggressive hydration, and electrolyte management***
- The patient exhibits **Tumor Lysis Syndrome (TLS)**, defined by **hyperuricemia**, **hyperkalemia**, **hyperphosphatemia**, and **acute kidney injury** (elevated creatinine) following induction chemotherapy.
- **Rasburicase** is the treatment of choice in established TLS as it converts existing **uric acid** into the highly soluble **allantoin**, rapidly reversing renal risk.
*Administer allopurinol and increase IV fluid rate to 200 mL/hour*
- **Allopurinol** is a xanthine oxidase inhibitor used for **prophylaxis**; it prevents new uric acid synthesis but does not break down existing crystals.
- In the setting of an **acute uric acid level of 12.5 mg/dL**, allopurinol is insufficient to prevent further renal damage from urate nephropathy.
*Begin hemodialysis and discontinue chemotherapy permanently*
- While **hemodialysis** is an option for refractory TLS with severe electrolyte imbalances, medical management with **rasburicase** and hydration is the standard first-line intervention.
- Chemotherapy should be managed with caution, but "permanent discontinuation" is typically not indicated for a treatable complication like **leukostasis** or TLS.
*Give calcium gluconate and sodium polystyrene sulfonate only*
- These medications address **hyperkalemia** only and do not treat the underlying **hyperuricemia** or **hyperphosphatemia** causing the acute kidney injury.
- **Calcium gluconate** is used for cardiac stabilization but does not lower potassium levels or treat the **TLS** components.
*Administer febuxostat and continue current chemotherapy regimen*
- Like allopurinol, **febuxostat** is a xanthine oxidase inhibitor used primarily for **prevention** and lacks the rapid efficacy of rasburicase in treatment.
- Continuing chemotherapy without first stabilizing the metabolic crisis of **Tumor Lysis Syndrome** would worsen the patient's **renal failure** and hyperkalemia.
Question 9: A 62-year-old man with metastatic colorectal cancer is started on FOLFOX chemotherapy (5-fluorouracil, leucovorin, and oxaliplatin). After the first cycle, he develops numbness and tingling in his fingers that worsens when he drinks cold beverages. Apply the appropriate management strategy for this patient's symptoms.
A. Discontinue oxaliplatin permanently and continue with 5-FU/leucovorin only
B. Reduce oxaliplatin dose and prescribe gabapentin for neuropathy (Correct Answer)
C. Continue current regimen and add IV calcium and magnesium infusions
D. Switch to irinotecan-based chemotherapy immediately
E. Hold oxaliplatin for 2 cycles then rechallenge at full dose
Explanation: ***Reduce oxaliplatin dose and prescribe gabapentin for neuropathy***
- **Oxaliplatin** is known to cause a unique **cold-induced neuropathy** characterized by dysesthesias; active management involving **dose reduction** is necessary to prevent persistent sensorimotor deficits.
- **Gabapentin** or duloxetine are pharmacological mainstays used to manage the neuropathic symptoms and improve the patient's quality of life during treatment.
*Discontinue oxaliplatin permanently and continue with 5-FU/leucovorin only*
- Permanent discontinuation is typically reserved for **Grade 3 or 4 neuropathy** that interferes with activities of daily living, rather than initial mild sensory symptoms.
- Discontinuing a primary agent prematurely may negatively impact the **therapeutic efficacy** of the metastatic colorectal cancer treatment regimen.
*Continue current regimen and add IV calcium and magnesium infusions*
- While previously common practice, clinical trials have shown that **calcium and magnesium infusions** do not effectively prevent oxaliplatin-induced **neurotoxicity**.
- Continuing the full dose without adjustment when symptoms are present increases the risk of developing irreversible **chronic peripheral neuropathy**.
*Switch to irinotecan-based chemotherapy immediately*
- Switching to **FOLFIRI** (irinotecan-based) is a strategy for disease progression or intolerance, but is not the first-line management for manageable **side effects** like neuropathy.
- The goal is to maximize the benefit of the current **first-line regimen** through appropriate supportive care and dose titration.
*Hold oxaliplatin for 2 cycles then rechallenge at full dose*
- Rechallenging at the **full dose** after a hold is likely to result in the immediate recurrence and worsening of the **neuropathic symptoms**.
- Management strategies focus on **dose modification** rather than temporary holds to maintain a steady state of chemotherapeutic control while minimizing toxicity.
Question 10: A 45-year-old woman with metastatic breast cancer presents with severe nausea and vomiting 24 hours after receiving her first cycle of doxorubicin and cyclophosphamide chemotherapy. She has tried ondansetron without relief. Her ECG shows QTc of 380 ms, and she has no history of cardiac disease. Apply the appropriate antiemetic management for this patient.
A. Add metoclopramide to the ondansetron regimen
B. Switch to aprepitant and continue ondansetron (Correct Answer)
C. Discontinue ondansetron and start prochlorperazine
D. Add lorazepam to the current ondansetron therapy
E. Replace ondansetron with dronabinol
Explanation: ***Switch to aprepitant and continue ondansetron***
- Doxorubicin and cyclophosphamide are considered **highly emetogenic chemotherapy (HEC)**, which requires a multi-drug regimen including an **NK1 receptor antagonist** like aprepitant.
- **Aprepitant** effectively targets the substance P/neurokinin 1 pathway to manage both **acute and delayed emesis** when combined with 5-HT3 antagonists like ondansetron.
*Add metoclopramide to the ondansetron regimen*
- Metoclopramide is a **dopamine D2 antagonist** that is generally less effective than NK1 antagonists for emesis caused by **highly emetogenic protocols**.
- While it can be used for breakthrough nausea, it does not address the underlying **delayed emesis** mechanism as effectively as adding a drug from a different class like aprepitant.
*Discontinue ondansetron and start prochlorperazine*
- Prochlorperazine is a **phenothiazine** used for mild-to-moderate nausea, but it is **insufficient as monotherapy** for a patient on an AC (Anthracycline/Cyclophosphamide) regimen.
- Discontinuing the **5-HT3 antagonist** (ondansetron) would likely worsen the patient's condition, as it is a backbone of HEC emetic prophylaxis.
*Add lorazepam to the current ondansetron therapy*
- Lorazepam is a **benzodiazepine** primarily used for **anticipatory nausea** or as an adjunct to enhance the efficacy of other antiemetics through sedation and anxiolysis.
- It is not the most appropriate next step for **high-grade emesis** resulting from the direct physiological triggers of highly emetogenic chemotherapeutic agents.
*Replace ondansetron with dronabinol*
- Dronabinol is a **cannabinoid** typically reserved as a **second-line or rescue therapy** for patients who have failed several standard antiemetic regimens.
- Replacing a **5-HT3 antagonist**, which is highly effective for acute emesis, with a cannabinoid is not recommended by current oncological guidelines for HEC management.
