Hello, there

On February 8^th, the day following my seventh Nexviazyme infusion, I met with my Pompe specialist for the first time since switching from Lumizyme (after completing nine years on that medication) to Nexviazyme.

If you’re just checking in on this blog for the first time, I reported some exciting news that arose around the time of my sixth Nexviazyme infusion. I’ve been dependent on a non-invasive ventilator 24/7 for about six or seven years. Pompe Disease has so weakened my diaphragm muscles that I’m just barely able to breathe on my own. I began using a bipap machine at night in 1996 following a two-week stay, intubated, in the intensive care unit. I had developed a severe pneumonia that nearly claimed my life. Once my lungs had cleared enough to take me off the breathing tube, we learned that, when I fell asleep, I would stop breathing. I acquired my first bipap machine at that time. It would be sixteen more years before we’d learn that I had Pompe Disease and that diaphragm weakness and ventilation were kinda par for the course. By the time of my Pompe diagnosis in 2012, my diaphragm was pretty well shot, and it wasn’t much longer before I needed breath support during the day. So, around 2014-2015, I had switched over to a non-invasive ventilator that I could tote around on my wheelchair. By that time, my forced vital capacity (i.e., breathing strength) was measured at 23% of normal. It’s a wonder I lasted that long without 24/7 assistance!

During the normal activities of my days, there are times when I need to remove my ventilator – when I’m showering, dressing, brushing my teeth, or transitioning from my daytime vent to my nighttime vent at bedtime. For the past many years, I’ve only been off my ventilator for a couple of minutes before I get panicked and grasp for my ventilator hose to catch my breath.

Well, around the time of my sixth Nexviazyme infusion, I discovered that my breathing strength was noticeably improving. When off my vent for a few minutes, I was able to sustain my breathing on my own. There were even times that I forgot to put my mask back on for minutes and minutes. Very unusual. The first few times this happened, I chalked it up to just having “a good day.” But after a sustained pattern of easier breathing that lasted days and then weeks, it became evident that something had changed. My morning care providers also noticed this change and commented that it looked like I was doing better. And I was. And I am!

I emailed my Pompe specialist and Genetic Counselor with this news when it developed. But our visit on February 8^th was our first chance to discuss this exciting news and our first real face-to-face conversation (albeit online) since I switched from Lumizyme to Nexviazyme on November 15^th.

We have communicated through email since making the switch … many times. There were a lot of hurdles involved in getting my Nexviazyme infusions started, mostly involving insurance approvals. These details are documented elsewhere in this blog. But there have also been some minor snags associated with the chain of authority among my Pompe specialist, my primary care physician, my infusion center pharmacy, and my infusion center staff. Again, those have been documented in other entries but suffice it to say that anytime even a minor tweak takes place in my weight, my infusion orders, or anything else, it triggers a complex chain of necessary approvals.

I communicate with a handful of fellow Pompe Disease patients who have also made the switch from Lumizyme to Nexviazyme. Almost all of those other folks pretty much jumped from one drug to the other without any major adjustments in the published standard of care. One or two were required to remain at their infusion centers following their first or second Nexviazyme infusion and then that requirement was dropped.

My Pompe specialist is being exceptionally cautious, relative those supervising other Pompe patients. We began my Nexviazyme infusions with half hour intervals between my initial three rate increases (as opposed to fifteen minutes. I was also required to stay at my infusion center for two-hour observation periods for my first few infusions. My specialist also required pre-medication of Solu Medrol prior to starting my infusions. Due to a miscommunication, that drug was placed in my crash cart in case of emergency rather than administered ahead of the infusion as a preemptive measure.

I asked my specialist during our visit why we were taking such a cautious approach when others have been up and running without such precautionary measures. My doctor explained to me that (1) mine is a very advanced case of Pompe Disease. If I develop an allergic reaction to this new drug, it’s possible that that reaction could also extend back to Lumizyme. If that were to happen, I’d be unable to receive my prescribed doses of either Lumizyme or Nexviazyme while we backtrack and try to slowly reintegrate one or the other of those drugs. If that were to happen, she explained, the losses I might experience from going without enzyme replacement therapy could be unpredictable at best and catastrophic at worst. My doctor also explained to me that (2) she has supervised enzyme replacement therapies for other patients with glycogen storage diseases where they have developed allergic responses after as much as a year of uneventful infusions. In some of those cases, she explained, she had to walk back infusions and basically start all over, rebuilding in baby steps. She explained that, once you’ve lost valuable ground like that, you learn to be very cautious. I couldn’t disagree with her approach.

After completing my first three Nexiazyme infusions with no adverse reactions, we reduced my observation period from two hours to one hour. We will continue with that practice until further notice.

After my sixth Nexviazyme infusion, we reduced the time interval between my first three rate increases from thirty minutes to fifteen minutes. This change cut about 25 minutes off of my infusion time, dropping it down to about three and a half hours.

During our February 8^th conversation, we discussed continuing with this protocol through my tenth infusion (so two more after today). If all continues going well, my doctor will prescribe an entirely new rate structure for Nexviazyme. That change will reduce my overall infusion time by probably another half hour. If I successfully tolerate that change, she has plans for other rate changes with the ultimate goal of bringing my overall infusion time down to 2 to 2.5 hours! That’s an enticing incentive; historically, my infusion days have tended to run about five hours with check-in, setup, and check-out. To achieve this new goal, we will likely be retaining one-hour observation periods until we get there and maintain stability. But this is definitely something to look forward to.

In our conversation, we discovered that my doctor’s preferred administration of Solu Medrol BEFORE each infusion wasn’t taking place. (I hadn’t been aware that she wanted me to take this drug before my infusions.) But since I’ve successfully tolerated seven Nexviazyme infusions by this discovery, my doctor agreed that we don’t want to fix what seems to be working. So I will continue to receive my Nexviazyme infusions with my only pre-medication being a single 500mg Tylenol a half hour before we start.

I also have an appointment next week – March 3^rd – for a visit to Sacramento to visit the University of California Davis Medical Center, Department of Physical Medicine & Rehabilitation. During this visit, I will receive comprehensive strength tests to establish new baseline measures. In the coming months, we will take other strength tests and measure them against these new baselines. I will also receive my first Pulmonary Function Tests (PFTs) to establish a new baseline for my breathing strength. Since I’ve been ventilated 24/7, we’ve stopped measuring my PFTs. But since it appears that my breathing in improving, we want to get a new baseline so we can objectively measure future scores against now. I will also get a new set of lab work done including my first HEX4 urine tests since starting Nexviazyme. The HEX4 urine test measures how the body is expelling glycogen. The symptoms of Pompe Disease are caused by the toxic accumulation of unconverted glycogen in our muscle tissues. We took this measure right before I started Nexviazyme. A new measure three months later will ideally show a similar or (preferably) better rate of glycogen expulsion.

So, the highlights of my first check-in since starting Nexviazyme:

1. My breathing appears to be improving! On March 3^rd, I’ll receive my first Pulmonary Function Tests in years to establish a new baseline. This will allow us to take future measurements against this baseline to determine objectively if my breathing strength is improving.
2. I’m successfully tolerating Nexviazyme. My doctor is not going to recommend pre-medication except for Tylenol. We have reduced my observation period and will keep it at one hour while we continue to periodically adjust my infusion rates over the coming months. The next rate adjustment could come as early as my first infusion in April. If I continue to tolerate Nexviazyme without incident, our goal is to increase my rate structure until my overall infusions are completed in 2-2.5 hours!
3. On March 3^rd, we’ll get my first objective muscle strength tests in several years and establish a new baseline of arm, leg, neck, and trunk strength, against which future measurements will be taken.
4. On March 3^rd, we’ll get our first objective before-and-after measurement since starting Nexviazyme. The HEX4 urine test will provide a measurement of how much glycogen my body is expelling. This will be compared to the test I had taken just before making the switch.

This blog entry comes as I’m about halfway through my eighth Nexviazyme infusion; today marks my 245^th enzyme replacement therapy infusion since starting them in September 2012.

I’m happy to be alive and optimistic about this unfolding next chapter in a life with Late Onset Pompe Disease!

Let Hope Flow!

~ Brian