Cancer experts have known for years that delivering chemotherapy directly into the arterial supply of the eye can blast a tumor with 250 times more impact than traditional IV delivery and yet use just 10 percent of the overall dose.
But the approach has not been available to a significant segment of children with intermediate to advanced retinoblastomas because the treatment is sometimes associated with a reversal of blood flow in the eye, washing away the medication instead of delivering it to its target.
When this problem occurs, traditional approaches to deliver chemotherapy to the eye can be ineffective, leaving physicians with no other option except to surgically remove the eye - until now. Todd Abruzzo, MD, Chief Interventional Neuroradiologist at Cincinnati Children’s, has combined a double-catheter approach with a medication that boosts the effectiveness of chemotherapy that can benefit nearly any patient with retinoblastoma.
“This combination therapy is more effective for all patients with retinoblastoma, not just those with unfavorable blood flow patterns,” Abruzzo says. “Our chances of achieving a long-term remission and preserving the eye are much improved by using this approach.”
Already one of the world’s top centers for intra-arterial chemotherapy, Cincinnati Children’s is the first to use this new method for selective ophthalmic artery infusion chemotherapy (SOAIC). Since 2011, Abruzzo has performed 42 procedures for 11 patients using this new technique, without a single technical failure. He has presented findings from these cases at two major medical conferences.
The concept of using the ophthalmic artery to infuse a tumor with chemotherapy was introduced in the 1950s in Japan – but it wasn’t until 1988 that the first catheter-based procedure was introduced. The treatments involved inserting a catheter into the femoral artery near the groin then threading it along a series of increasingly narrow vessels until it reaches the intracranial carotid artery, from which a branch leads to the eye.
However, early catheters were too large to make the final turn into the narrow ophthalmic artery. So to make the procedure work, doctors inflated a balloon above the branch point like a road block that forces the chemotherapy to turn down the branch. The drawback to this approach is that the balloon block disrupts blood flow to the brain.
By 1993, a catheter no thicker than a strand of angel hair pasta was developed that could be steered directly into the narrow ophthalmic artery. This breakthrough allowed doctors to achieve remission in about 80 percent of retinoblastoma patients who had not received prior treatment.
Unfortunately, the ophthalmic artery is so narrow in some patients that even the tiny catheter cuts off too much blood. When this occurs, it changes the pressure balance in the artery, causing blood flow to reverse and carry the chemotherapy away from the tumor.
Abruzzo solved the problem by threading a second catheter along the patient’s other femoral artery and into the external carotid artery. Inflating a balloon at a point along this route causes a beneficial pressure change that pushes chemotherapy to the tumor without cutting off blood flow to the brain.
He improved the technique further by administering verapamil, a drug that increases the flow of chemotherapy to the tumor and blocks the tumor’s ability to pump chemotherapy away before it does its job.
Only time will tell how much impact the new treatment has on tumor-free remission rates, but Abruzzo expects outcomes will improve.
“This is a robust and reproducible approach,” Abruzzo says. “We’ve been able to use this technique to treat infants as small as 6.5 kilos (14.5 pounds). We’ve also been able to deliver therapy to both eyes in the same session.”