Marker lesion experiments in bladder cancer--what have we learned?

Area of Science:

• Oncology
• Urologic Oncology
• Clinical Trials

Background:

• Marker lesion studies involve leaving a single bladder tumor unresected for targeted therapy evaluation.
• Assessing the safety and ethics of marker lesion studies is crucial alongside treatment efficacy.
• These studies offer a unique opportunity to measure therapeutic effects on existing disease.

Purpose of the Study:

• To review the goals, inclusion criteria, success definitions, agents, effectiveness, safety, and ethics of marker lesion studies.
• To propose a framework for conducting future marker lesion experiments.
• To evaluate the utility of marker lesion studies in assessing novel anticancer therapeutics.

Main Methods:

• A systematic MEDLINE search was conducted for published bladder cancer studies utilizing the marker lesion concept up to March 2009.
• Identified studies were analyzed for agents used, patient populations, response rates, and safety outcomes.
• A total of 23 studies involving over 1,200 patients were included in the review.

Main Results:

• Commonly studied agents included cytotoxins (e.g., mitomycin-C, apaziquone) and immune response modifiers (e.g., bacillus Calmette-Guerin).
• Apaziquone demonstrated the highest complete response rate (67%) in intermediate-risk patients, with improved recurrence-free survival.
• Bacillus Calmette-Guerin trials showed complete response rates ranging from 32% to 61%.
• Marker lesion studies were generally safe, with a low rate of disease progression (0.6%).

Conclusions:

• Marker lesion studies are highly appropriate for evaluating novel anticancer therapeutics in bladder cancer.
• Patient selection should be restricted to those with multiple recurrent, noninvasive, low-grade tumors (intermediate risk).
• Primary endpoints should focus on complete response and recurrence rates assessed over 2 to 3 years.