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An Orthotopic Bladder Cancer Model for Gene Delivery Studies
Published on: December 1, 2013
Marker lesion experiments in bladder cancer--what have we learned?
Ofer N Gofrit1, Kevin C Zorn, Sergey Shikanov
1Department of Urology, Hadassah Hebrew University Hospital, Jerusalem, Israel. ogofrit@gmail.com
Purpose:
In marker lesion experiments a single bladder tumor is deliberately left unresected for later ablation by intravesical instillation of a novel agent. While the benefits are clear, eg the opportunity to examine the effect of therapy on measurable disease, the safety and medical ethics of these experiments are less obvious. We review the goals, inclusion criteria, definition of success, agents used, effectiveness, safety and ethics of marker lesion studies, and suggest a framework for future experiments.
Materials And Methods:
Published bladder cancer studies using the marker lesion concept were identified with a MEDLINE search through March 2009.
Results:
A total of 23 well documented marker lesion studies were identified involving more than 1,200 patients. Most agents studied were cytotoxins (mitomycin-C, epirubicin, gemcitabine, valrubicin, apaziquone) or immune response modifiers (bacillus Calmette-Guerin, tumor necrosis factor-alpha, interferon-alpha, granulocyte-macrophage colony-stimulating factor). The highest complete response rate in intermediate risk patients (67%) was attained with apaziquone. Patients who achieved a complete response with this agent also had a prophylactic benefit with a 2-year recurrence-free rate of 45.2% compared to 26.7% in those who did not achieve a complete response. The complete response rate in bacillus Calmette-Guerin trials ranged from 32% to 61%. Marker lesion experiments were deemed safe with progression to T2 disease in only 7 patients (0.6%) and only when high risk patients were selected.
Conclusions:
Marker lesion studies are most appropriate for the evaluation of novel anticancer therapeutics. Only patients with multiple recurrent, noninvasive, low grade tumors (intermediate risk) should be recruited. Primary end points should be complete response and recurrence rates after 2 to 3 years.
Insights
Marker lesion studies are valuable for testing new bladder cancer treatments. These studies showed good safety and effectiveness, especially with apaziquone, for intermediate-risk patients.
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.
