Clinical Trial: Combination of Radiation and Microwave Ablation to Treat Kidney Cancer

Surgery is the standard treatment for most kidney cancers, but not all patients are able or willing to undergo such procedures. Fortunately, there are other options, including microwave ablation, a procedure that destroys tumors with heat generated by microwave energy delivered through a narrow antenna inserted into the tumor. This procedure works well for treating small kidney tumors but becomes less effective when tumors are larger than four centimeters. That’s where radiation therapy may help.

An interdisciplinary team of University of Wisconsin School of Medicine and Public Health faculty have begun a Phase 1 clinical trial to study whether combining microwave ablation with stereotactic radiation can improve the treatment of kidney cancer over microwave ablation alone. This trial will assess the safety of combining these two treatment methods.

“Our hope is that the two treatments synergize and provide more than just an additive benefit,” says Dr. Michael Bassetti, assistant professor of Human Oncology.

The idea for this clinical trial came from former UW Radiation Oncology Chief Resident Dr. Andrzej Wojcieszynski, who was exploring potential use of radiation to treat kidney cancer. He developed the idea for combining microwave ablation with stereotactic radiation in consultation with Bassetti, Drs. Fred Lee, professor of Radiology, and Jason Abel, associate professor of Urology.

“I am excited about this trial because it investigates a minimally invasive alternative treatment for kidney cancer,” Abel says. “This novel approach may provide an option for patients who are ill and not able to be treated surgically.”

Stereotactic radiation is not a common treatment for kidney cancer, mainly because of the sensitivity of normal kidneys to radiation and the difficulty of accurately targeting tumors in parts of the body that move as a person breathes. However, advances in MRI-guided radiotherapy have improved delivery of radiation to areas that are difficult to target. The UW Radiation Oncology Clinic is just one of a handful of institutions in the world to have a ViewRay MRIdian, an MRI-guided radiotherapy system that enables continuous imaging of tumors and normal tissues during treatment to improve accuracy.

“With MRI guidance during radiation treatment we can see the kidneys movement during treatment. This lets us target radiation to the tumor while avoiding radiation to the remaining kidney. Our hope is that this may help preserve the remaining kidney function,” Bassetti says.

The trial will consist of three cohorts. The first will receive a moderate dose of radiation, and depending on how well the patients tolerate it, subsequent cohorts will receive higher doses. For each cohort, the radiation treatment will be followed by microwave ablation a couple of months later.

Treating these patients with stereotactic radiation before ablation may reduce bleeding risks during the microwave ablation. In addition, combining these therapies may help reduce side effects.

“This trial is an excellent example of the synergies that are possible between treatment modalities applied in a systematic multidisciplinary manner, and the ability to conceive and execute the trial is a testament to the urology, human oncology and radiology teams here at UW,” Lee says. “If successful, this trial should enable us to treat larger and more complex tumors more safely.”

In addition to assessing the safety of combining these two therapies, the team hopes to be able to collect tissue samples before and after radiation treatment to see how the radiation affects immune system response.

“A question for a future trial is, would these treatments of microwave ablation and stereotactic radiation be synergistic with drugs that trigger the immune system to attack cancer?” Bassetti says. “We’re very interested in the immune response because radiation has been shown to be immunogenic. Could we further improve outcomes by combining these treatments with immunotherapy drugs?”