Trial Information

A Prospective, Randomized, Active-Control, Multi-Center Study Assessing Overall Survival Using Chemotherapy With or Without Impedance-Based Radiofrequency Ablation for Subjects With Colorectal Cancer and Incurable Metastatic Liver Disease, Failing at Least First-Line Chemotherapy

The American Cancer Society has estimated that colorectal cancer is the second leading cause
of cancer related deaths, with 106,370 new cases diagnosed in 2004. Due to the unique
nature of the hepatic circulatory system, with preferential portal venous drainage of the
gastrointestinal tract, the liver is the most common site for metastatic tumor growth from a
colorectal carcinoma. It is estimated that approximately 20% of patients diagnosed with
colorectal cancer will present with liver involvement at the time of diagnosis, and 50% of
patients will manifest metastatic involvement of the liver following resection of the
primary colorectal cancer. Over one half of patients who die of colorectal cancer have
liver metastases at autopsy.

The current "gold standard" in the treatment of isolated metastatic liver disease is
curative hepatic resection. Only within the last 20 years has surgical resection become a
viable option, as in the past it was considered unjustified due to high morbidity and
mortality rates. The primary drawback to hepatic resection is the sheer number of patients
for whom it is contraindicated. Only 10-20% of patients liver metastases are candidates for
surgical resection, owing to factors such as tumor locations, size, extent of disease, and
other medical co-morbidities.

Historically, in cases where hepatic resection was contraindicated, systemic chemotherapy
was the only alternative treatment. In the last several years an increasing number of
hepatic directed therapies have become available such as hepatic artery ligation, radiation,
hepatic artery infusion of chemotherapy, chemoembolization, and mechanical ablation of the
tumor(s).

One mechanical method of ablation involves the use of radiofrequency thermal technology,
also called radiofrequency ablation (RFA). The RFA procedure involves inserting an RF
electrode into the center of a hepatic tumor mass under ultrasonic or CT guidance.
Radiofrequency energy is then applied through the electrode, causing a thermal injury to the
surrounding tumor tissue. Currently there are two basic designs for monitoring
inter-procedural progress during RFA; temperature monitoring of set points within the target
tissue with thermocouples, or assessing the system-wide impedance of tissue adjacent to the
deployed electrode tines. Radiofrequency ablation systems are comprised of three components:
a radiofrequency generator, an active electrode, and dispersive electrodes.

To date no prospective multi-center trials have been completed which would conclusively
demonstrate whether RFA is an effective adjunct to systemic chemotherapy with respect to
advantages in median overall survival compared with chemotherapy alone. The primary
objective of this trial is to determine overall survival for subjects with colorectal cancer
and incurable metastatic liver disease who fail at least first line chemotherapy and are
treated with radiofrequency ablation plus additional chemotherapy, compared to subjects
receiving additional chemotherapy only.