Sunday, March 4, 2018

Gleevec/Imatinib For Mast Cell Activation Syndrome

I began my trial of Gleevec, a drug belonging to the class of Tyrosine Kinase Inhibitors (TKIs), November of 2015...but let's back up. There are a few pertinent details that I must mention first.

I had already been inpatient at the hospital for over a month due to a Mast Cell Activation Syndrome flare up. I was stuck in a severe reaction cycle. I was unable to tolerate food and IV nutrition. Thus, my medical team contacted a specialist and then implemented the Continuous Diphenhydramine Infusion (CDI) in attempts to gain control of my symptoms.

A continuous infusion of Benadryl was not the most appealing of treatment options, nor were the massive amounts of IV steroids. The goal was to find an alternative that could take over what those medications were doing. With a lack of published studies on the CDI at the time, my medical team wanted to ensure I was not sent home on it. That is why oncology was consulted to trial Gleevec. Little did I know, I would remain inpatient at the hospital another four months.

I did document a portion of my trial well over two years ago in Gleevec and CDI Experience Update: Not My Miracle Cure. It was at the beginning of my blogging journey. Now that I am rereading, the initial post is incomplete and lacks answers to the common questions I am often asked regarding the treatment.


The process of adjusting the Gleevec dose was lengthy. My doctors and I agreed to go very slow because of my history of medications sensitivities. A dose of 200 mg is typically the "sweet spot" for Mast Cell Activation Syndrome patients. Many do not notice any benefits prior to reaching that dose. My starting dose was a measly 25 mg once a day to test my response. I worked up to 25 mg twice daily after we determined whether or not I would have a severe, immediate reaction.

My dosing was increased in three day increments until I reached a dose of 100 mg as my total dose. Unfortunately, the oncologist decided to reinvent the wheel, so to speak, and did not abide by the plan of the specialist. The oncologist refused to increase to the dose known to be therapeutic for my condition. I spent an entire month on 100 mg with no benefits. Eventually, the dose was increased to 150 mg for one week before going up to 200 mg.


Gleevec cannot be compounded. It contains ingredients that are likely to trigger a reaction for sensitive patients —the red outer coating being one of them. The majority of patients trial Gleevec at home on an outpatient basis where taking the outer coating off is recommended to avoid a reaction to the excipients.
How to remove the coating:
1. Heat 20-30 mL of water in the microwave.
2. Submerge pill in the warm water for 5 seconds. 
3. The coating will peel away from the pill. 
4.  Take tweezers to remove the coating. 
Since I was inpatient, the hospital pharmacy was not legally allowed to have the coating removed. I was exposed to all of the ingredients in the coating.

I took Gleevec via my GJ feeding tube. The pill could not be crushed, so it was diluted in 30 mL of water, put into a syringe, and administered into the G port of my feeding tube. It is best to take the medication with food because it is harsh on the gastrointestinal tract. I did not tolerate food or tube feedings directly in my stomach. However, I ran J tube feedings before and after each dose to be safe.


Like already mentioned, I noticed no improvements with the doses that were 100 mg or less. The 150 mg and 200 mg doses did prove to be slightly helpful! Within 36 hours of the 150 mg dose, I had a substantial decrease in POTS symptoms. My standing pulse had not been less than 150 beats per minute since July of that year and most of the time it had been hanging around 200 beats standing. With Gleevec, my standing pulse was between 100-110 and rarely exceeded 130. I was still having blackout episodes and losing vision and hearing upon standing, but my pulse was much better. There was also a reduction in the tremors in my hands, arms, and legs. My general overall "reactiveness" improved about 10-15%. Much to my disappointment, increasing to the 200 mg dose did not result in further improvement.

Side Effects

Towards the beginning of the trial, I had no side effects with the smaller doses from the drug itself. Yet, it did provoke Mast Cell Activation symptoms. The initial reactions from Gleevec did not differ from the reactions I had been experiencing to my other medications, water, and J tube feedings.

GI symptoms were a concern, but Gleevec did not cause nausea and it did not increase daily episodes of diarrhea. I did have intestinal pain correlated with my dose, especially in the evenings.

True side effects did not have a vast impact until I was a couple of weeks into the 100 mg dose. My blood counts began to drop—particularly my hemoglobin, hematocrit, and red blood cells. The counts were nearing transfusion level. Each week they would drop more.

The drug is also infamous for causing an imbalance of electrolytes. I had additional issues with low potassium. Supplementation via IV was enough to normalize the level.

Immune suppression is not ideal when relying on a central line. I had it from both Gleevec and high dose steroids (200 mg SoluCortef). While Gleevec provided modest relief, it was not decreasing the amount of Benadryl required to treat reactions. I remained very much dependent on my central line for the CDI and other IV medications. We wanted to give the Gleevec more time to work. So, my steroids had to be weaned to lessen my risk of infection. It was one or the other.

As the steroids were weaned, I gradually stopped tolerating the Gleevec. The pharmacist happened to walk in the hospital room in the middle of a reaction triggered by my evening Gleevec dose. The reactions entailed flushing, tachycardia, tremors, facial swelling, and throat swelling that was the deciding factor to stop the medication. She texted the entire medical team immediately and the Gleevec was discontinued from my treatment.

Gleevec was not my miracle cure. Had I not developed progressive reactions to the drug, it is probable that it would have to have been discontinued for its impact on my blood counts. I do not regret trying though. It was worth a shot!