Using CT-scan images to steer gene-therapy injections directly into tumors offers a safe delivery method for treating patients with metastatic kidney cancer, according to an article in the May issue of Radiology. The new findings may enhance treatment of the disease, which resists traditional intravenous chemotherapy in 85 percent of cases.

“Gene therapy offers great promise for controlling certain types of cancer,” explained Robert Suh, MD, lead author of the study. “But our challenge was to deliver therapeutic genes directly into tumors in delicate tissue like the lung, which is easily punctured. The CT-scanner provided a detailed visual image that enabled us to precisely locate the tumor inside the body and to safely pinpoint the injection site.”

The only treatment currently approved in the US is recombinant interleukin-2 (IL-2), which produces a 15-percent response rate when given intravenously. Serious and often life-threatening side effects limit IL-2 from wide use.

Scientists have developed several gene-therapy agents to improve IL-2’s effectiveness and minimize its side effects. In the current study, researchers studied whether images from a CT-scanner enhanced their ability to safely position a needle in both shallow and deep tumor sites to inject a gene that encodes for IL-2.

“Monitoring the CT-scan images enabled us to precisely target the tumor,” said Suh. “It eliminated any guesswork about where to angle the needle and how deeply to inject the therapy.”

The team performed 284 CT-guided injections on 29 patients with metastatic kidney cancer. Each patient received up to 3 cycles of 6 weekly injections. In each case, the researchers successfully injected the therapeutic agent into the tumor.

None of the patients experienced serious side effects. Minor complications occurred in 14.8 percent of injections; complication rate did not increase with the number of injections. The most common complication was air collection in the chest, a condition for which a single patient required drainage. Patients received local anesthesia around the injection site each time and tolerated the weekly procedure well, according to Suh.

“Our findings validate that CT-guided injection of therapeutic genes is safe and feasible,” he concluded.