Examkin

Question

Difficulty: Very hardNeoplastic Processes

A 64-year-old man with chronic hepatitis C virus infection is evaluated for abdominal distension, fatigue, and a 5-kg5\text{-kg} (11-lb11\text{-lb}) weight loss over the past two months. Three weeks ago, he was admitted to the hospital for an episode of hematemesis. Esophagogastroduodenoscopy at that time revealed large esophageal varices with red wale signs; he received endoscopic band ligation and was discharged on nadolol.

Vital signs today are within normal limits. Physical examination shows scleral icterus, palmar erythema, and a palpable, hard liver edge 4 cm4 \text{ cm} below the right costal margin.

Laboratory studies show:
Total bilirubin: 2.4 mg/dL2.4 \text{ mg/dL}
Aspartate aminotransferase (AST): 95 U/L95 \text{ U/L}
Alanine aminotransferase (ALT): 88 U/L88 \text{ U/L}
Platelet count: 85,000/μL85,000/\mu\text{L}
Alpha-fetoprotein: 2,100 ng/mL2,100 \text{ ng/mL}

A multiphase abdominal CT scan reveals a 7-cm7\text{-cm} hypervascular mass in the right hepatic lobe that demonstrates avid arterial phase enhancement and rapid portal venous washout. The mass invades the right main branch of the portal vein. There is no evidence of extrahepatic metastasis.

The multidisciplinary tumor board considers initiating the preferred first-line systemic combination regimen consisting of atezolizumab and bevacizumab. However, the oncologist determines that this specific regimen is currently contraindicated for this patient.

This contraindication is primarily due to the drug-induced impairment of which of the following physiological processes?

  1. Endothelial cell migration and maintenance of vascular structural integrityAnswer
  2. B
    Cytotoxic T-lymphocyte self-tolerance and prevention of autoimmune tissue damage
  3. C
    Cytochrome P450 3A4-mediated biotransformation and clearance of active metabolites
  4. D
    Vitamin K-dependent gamma-carboxylation of circulating coagulation factors
  5. E
    Thrombopoietin-driven megakaryocyte differentiation and platelet production

Answer

Endothelial cell migration and maintenance of vascular structural integrity.
The correct answer identifies endothelial cell migration and maintenance of vascular structural integrity. The patient has advanced hepatocellular carcinoma and requires systemic therapy. The standard first-line regimen is atezolizumab (an immune checkpoint inhibitor against PD-L1) plus bevacizumab (a monoclonal antibody against VEGF). Bevacizumab works by binding to circulating VEGF, thereby preventing it from activating the VEGF receptor on endothelial cells. While this effectively starves the tumor of its blood supply, VEGF is also essential for maintaining the structural integrity of normal blood vessels and facilitating mucosal repair. In a patient with portal hypertension and a recent history of high-risk bleeding from esophageal varices, inhibiting VEGF severely impairs the healing of the fragile variceal endothelium, leading to an unacceptably high risk of fatal gastrointestinal hemorrhage. Therefore, recent or untreated variceal bleeding is an absolute contraindication to bevacizumab. All patients require an esophagogastroduodenoscopy (EGD) within 6 months prior to initiating this therapy to treat high-risk varices.

Step-by-Step Solution

1
Diagnose the patient's primary condition.
Advanced hepatocellular carcinoma (HCC) with portal vein invasion.
The markedly elevated alpha-fetoprotein (2,100 ng/mL2,100 \text{ ng/mL}) combined with classic CT findings (arterial enhancement and portal venous washout) in a patient with cirrhosis confirms HCC.
2
Identify the standard first-line therapy being considered.
The combination of atezolizumab (anti-PD-L1) and bevacizumab (anti-VEGF).
This combination is the preferred first-line systemic therapy for advanced, unresectable HCC.
3
Correlate the patient's critical history with the pharmacological mechanisms of the proposed drugs.
The patient had a recent severe variceal bleed. Bevacizumab acts by inhibiting VEGF.
Evaluating contraindications requires matching the patient's comorbidities with the specific adverse effect profiles of the antineoplastic agents.
4
Determine the physiological consequence of VEGF inhibition in this specific patient.
Inhibition of endothelial cell migration and repair, leading to a high risk of catastrophic variceal hemorrhage.
VEGF is essential for maintaining the structural integrity of normal blood vessels and facilitating mucosal repair. Without it, the fragile varices cannot heal, making this the absolute contraindication to therapy.

Key Concept

Hepatocellular carcinoma targeted therapy and Bevacizumab contraindications.
Rate this question

Topics

Neoplastic Processes

More questions from this topic