Using CT-scan images to steer gene-therapy injections directly into the tumor offers a safe delivery method for treating patients with metastatic kidney cancer, report UCLA radiologists in the May issue of Radiology. Their findings could enhance the treatment of the disease, which resists traditional intravenous chemotherapy in 85 percent of cases.
Gene therapy enables doctors to introduce genetic material directly into cells to fight disease. In this study, UCLA radiologists positioned cancer patients in CT scanners before injecting therapeutic genes into their tumors.
"Gene therapy offers great promise for controlling certain types of cancer," said Dr. Robert Suh, assistant clinical professor of radiology and director of thoracic interventional services at the David Geffen School of Medicine at UCLA. "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 locate precisely the tumor inside the body and to pinpoint safely the injection site," said Suh, a member of UCLA's Jonsson Cancer Center.
Metastatic kidney cancer is stubbornly resistant to chemotherapy. The only FDA‑approved treatment, recombinant interleukin-2 (IL-2), 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 — which rely on direct injections instead of intravenous infusion — to improve IL-2's effectiveness and minimize its side effects.
For the first time, UCLA researchers studied whether images from a CT-scanner enhanced their ability to position safely 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 target the tumor precisely," Suh said. "It eliminated any guesswork about where to angle the needle and how deeply to inject the therapy."
The UCLA team performed 284 CT-guided injections on 29 patients with metastatic kidney cancer. The patients received up to three cycles of six 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. The most common complication was air collection in the chest — for which one patient required drainage.
The patients received local anesthesia around the injection site each time and tolerated the weekly procedure well, Suh said. The complication rate did not increase with the number of injections.
"Our findings validate that CT-guided injection of therapeutic genes is safe and feasible," Suh said.
The biotechnology firm Vical funded the study. Suh's UCLA co-authors included Dr. Jonathan Goldin, Dr. Amanda Wallace, Dr. Ramon Sheehan and Dr. Stefan Heinze, as well as UCLA's Jonsson Cancer Center members Dr. Barbara Gitlitz and Dr. Robert Figlin.