Comparing an Antireflux Catheter to Standard End-Hole Catheter for Y90 Treatment of HCC: An Interview With Alexander Pasciak, PhD

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Alexander Pasciak, PhD, is a physicist and researcher at the University of Tennessee Medical Center. At the 2015 Annual Scientific Meeting of the Society of Interventional Radiology (SIR), Dr. Pasciak, also a member of SIR, presented information on a study that he led to examine differences in hepatic distribution of embolic particles after infusion with a standard end-hole catheter vs an antireflux microcatheter, the Surefire Infusion System (Surefire Medical). Interventional Oncology 360 asked Dr. Pasciak to describe the study.  

IO360: Could you describe the trial and its methodology?

Pasciak: This trial was a prospective trial that I designed, and the goal was to evaluate the differences between a Surefire catheter and an end-hole catheter and its effect on liver-directed radioembolization. We don’t have sufficient patient volume at the University of Tennessee to support a traditional randomized study, so we put effort into obtaining statistically significant results through careful study design to narrow down a number of variables. We performed two infusions on each patient and we did these infusions on the same day, at the same site of infusion. The only thing that varied was the type of microcatheter that was used; we used an end-hole catheter for one infusion and the Surefire catheter for the other. 

All included patients had liver cancer, either metastatic or primary, and there were varying ranges in the tumor involvement in the liver. We exploited the mapping phase of a traditional radioembolization procedure, where technetium 99m macroaggregated albumin (MAA) to evaluate lung-shunt fraction, by using it to evaluate differences in distribution with the 2 catheter types in the liver. We did this using a novel protocol modeled off of routine renal and cardiac perfusion imaging. In routine cardiac perfusion, often when performing a stress-rest test, a small dose is injected in the morning, and either the rest or the stress portion of the study is completed, and then later on in the afternoon, the patient will come back and receive a much larger dose, followed by single-photon emission computed tomography (SPECT) after each one. On the second imaging will still be some residual left from the first procedure done in the morning, however, since there is so much more activity administered in the second portion of the procedure, any residual is overwhelmed.  We essentially did the same thing but with MAA. Each patient received two infusions: one with the Surefire catheter, one with the end-hole catheter, and we varied the infusion order among the patients: half received Surefire first, half received end-hole first.  A small MAA dosage was administered in the morning and brought them back in the afternoon and then infused a much larger MAA dosage. We left the sheath in, and after each administration, we took them to nuclear medicine, where they received SPECT imaging.  

A week or so later, we brought the patients back to treat them with the actual yttrium-90 embolization, and we used the Surefire catheter for all of the radioembolization procedures. Afterwards, all patients got an yttrium-90 PET/CT scan, which allowed us to see the distribution of the actual radioembolization itself.  It confirmed that the MAA that was administered with the Surefire catheter matched the distribution of radioembolic microspheres, and that validated our use of MAA as a radioembolization surrogate. 

We only had about 10 patients that were enrolled over the course of about a year, and part of the reason for the small sample size is that we have a relatively small practice, but also part of it is that the study is complicated and patients are going to receive 2 catheterizations instead of 1 so that’s troubling for some patients. However, because we used the same patients and did two consecutive infusions on the same day, we were able to get statistically significant results because the only variable was the microcatheter that was used. 

IO360: What were some of the more remarkable results?

Pasciak: Again, these were patients with either primary or metastatic liver cancer, with different tumor burdens. In almost all patients, we saw that there was an increase in deposition into the tumor, or penetration into the tumor. In every patient we saw decreases in MAA uptake into the normal liver tissue surrounding the tumor. That’s not to say that every patient an ideal treatment.  The antireflux catheter increased penetration, but it can’t get microspheres into areas of tumor that are not perfused by the blood supply that you are infusing from. The antireflux catheter isn’t magic, but it was better in all cases and some of the treatments were exceptional generating complete response for some of these patients and that’s something that we felt good about as well. 

Every patient was treated with the Surefire catheter and we couldn’t treat the same patient twice, so as the MAA portion allowed us to observe the difference in distribution, the fact that there was more tumor penetration, less MAA in normal liver, that can be a good thing. You can never have too much dose to the tumor and if you’re delivering less dose to the normal liver, there’s basically nowhere else for it to go but into the tumor so you see that as a good thing. We don’t have data to show difference in outcomes, obviously, because all of the patients were treated in the same way. To look at difference in outcomes would take a much larger, blinded study, which we haven’t completed yet. 

IO360: How about any limitations or caveats to the Surefire catheter?

Pasciak: From my perspective as a physicist, I didn’t really see any limitations. We had one device complication: On one of the embolizations, the catheter occluded and we had to basically start over. We got a new Surefire catheter, drew up a new dose of radioembolization that approximated the amount of the initial prescription that hadn’t yet been delivered, and we delivered that without further incident.  This occurred with either our second or third patient, so we attributed it to lack of familiarity with the device. It is a little bit different to use, you have to flush more, according to our interventional radiologist, who has now become very proficient in using this device. It just takes a little bit of getting used to, is how I understand it. 

IO360: What do you think the most important takeaway message is for an interventional oncology clinician about using the Surefire catheter?

Pasciak: I think that there are a lot of cases where Surefire could potentially benefit patients. In almost every case, from what we saw, you have the potential for getting more dose into the tumor. Now, that’s not going to help everyone, because again, radioembolization already works with an end-hole catheter for many patients. It’s certainly not going to help those people that would otherwise have complete response, but for people who are potentially borderline – maybe patients who have only partial response or who have a part of a tumor that’s more distal or downstream from the site of infusion and doesn’t get as much dose – the Surefire catheter could potentially increase the amount of radioactivity delivered to certain areas. Again, you could assume that that might make a difference in some of these patients’ outcome, however, I don’t have data to show that at this time.  I will say that if I were a patient receiving radioembolization, I would probably opt for Surefire because I think it could increase my chances of getting a good response.

IO360: How about the future for Surefire, are there any studies or devices in development?

Pasciak: There is a new device that’s coming out that is very exciting. There are some ongoing studies to continue the work that I’ve done, but I can’t go into much detail.

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Editor’s note: Disclosure: Dr. Pasciak has completed and returned the ICMJE Form for Disclosure of Potential Conflicts of Interest. He reports an unrestricted grant from Surefire Medical. 

Suggested citation: Ford J. Comparing an antireflux catheter to standard end-hole catheter for Y90 treatment of HCC: an interview with Alexander Pasciak, PhD. Intervent Oncol 360. 2015;3(6):E60-E62.