This entry will appeal to those who enjoy knowing the details of Enzyme Replacement Therapy (ERT), those evaluating a change from Lumizyme to Nexviazyme, and those who are curious about how initial infusions will be administered using the new drug. I can’t say that all prescribing Pompe Disease specialists will use the approach being recommended by my own, but this will provide details of what you might expect.
I dropped by the infusion center yesterday to get my current body weight … a necessary precursor to determining the dosage of my upcoming first Nexviazyme infusion on October 18th. While I was there, I asked for a copy of my initial infusion orders for the new drug so I’d know what to expect.
Having received 235 Lumizyme infusions to date, I’ve become accustomed to the +/- 4.5-hour infusion regimen of that treatment. From my conversations with my Pompe Disease specialist, I’ve been expecting that my first several Nexviazyme infusions would be at a slower rate so we can carefully monitor my responses. There is virtually no data to inform the process of longtime Lumizyme users moving over to Nexviazyme; all of the patients in the clinical trials were new to enzyme replacement therapy. So, out of an abundance of caution, we’re going to start slower than the ultimate prescribed rate.
My nine years of Lumizyme infusions have been administered according to that drug’s prescribed standard of care. This involves starting at a rate of 30 mL/hr. for 15 minutes. At 15-minute intervals, we’ve increased my rate by 60 mL/hr. until we reach a maximum rate of 210 mL/hr. At that pace, we reach my max rate in 60 minutes. At each of these intervals, we record my vital signs (i.e., blood pressure, pulse rate, temperature, oxygen saturation). Once we’ve reached that max rate, we take vital signs hourly until I’ve received the full 2,000 mg dose (based on my body weight). I’m not a small human being. At 6’4” and about 250 lbs., my Lumizyme dosage has been relatively high.
Reconstituted Lumizyme produces protein strands that are actually visible in the solution. Lumizyme is administered with a fine inline protein filter. Because my Lumizyme dosage is higher than the norm, we discovered early on that my filter would clog about 2 or 3 hours into my infusion. We would get an occlusion alarm and have to stop my infusion and change filters. As a remedy to this common occurrence, we had the pharmacy divide my medication into two separate infusion bags, each with its own inline protein filter. This extended the time of my infusions because we had to flush my infusion lines after the first bag and switch over to the second bag; but we saved the time of having to stop in the middle of my infusions to change filters. Generally, my Lumizyme infusions would take about 4.5 hours.
Nexviazyme has a very similar prescribed standard of care. With the new drug, my dosage will be slightly higher – 2,300 mg (vs. 2,000 mg of Lumizyme). Following the same protocol developed in my early years of Lumizyme infusions, my full Nexviazyme dosage will be divided into two infusion bags, each fitted with its own fine inline protein filter. The prescribed infusion rates and intervals are the same for Nexviazyme as they are for Lumizyme. However, because we want to closely monitor my physiological responses to this new drug, my initial orders double the time between rate increases. So, I’ll start my Nexviazyme infusion at 30 mL/hr. and stay at that rate for 30 minutes (instead of 15). We’ll record my vital signs at that point and, if all is stable, we’ll ramp me up 60 mL/hr. to 90 mL/hr. We’ll continue those 60 mL./hr. increases every 30 minutes until I reach the maximum rate of 210 mL/hr. Allowing 30 minutes between increases, it will take 2 hours to reach my max rate (versus the 1 hour I’m used to). And because the overall dose is greater, we expect it will take more like 6 or 7 hours to receive the full infusion (versus the 4.5 hours I’ve been used to). Because we are being exceptionally cautious and have no real frame of reference for how longtime Lumizyme users will respond to the change to Nexviazyme, I’ll also be required to stay at the infusion center for a 2-hour observation period after completing the infusion … just to be sure I don’t have a problematic reaction. So, all told, my first several infusion sessions with Nexviazyme will take more like 8-9 hours.
Again, this slower initial infusion rate is intended as a temporary protocol so we can carefully monitor my response to Nexviazyme. Once we feel confident that my body is adapting to the new drug, we’ll increase the infusion rates to the prescribed standard and my Nexviazyme infusions will be roughly comparable to the Lumizyme infusions. I don’t know how many Nexviazyme infusions will be administered at this slower rate or how many times I’ll be required to stay for an observation period. I think our plan is to start with the first infusion and see how it goes. Then, we’ll take it from there.
It’s worth mentioning that I never had an antibiotic or adverse reaction to Lumizyme. My body readily assimilated that drug from the start. I’ve also never required pre-medications with Lumizyme. For my first several Nexviazyme infusions, however, my specialists are prescribing pre-meds of Benadryl and Tylenol. Truth be told, I have more anxiety about the pre-meds than I do about the Nexviazyme. I’m not a big fan of being medicated or sedated. But my overall excitement about this change from Lumizyme to Nexviazyme more than offsets any anxieties.
… more to follow …