Research Results Out: Cancer drug slows PKD

There’s been alot of buzz over the last week or so on research released that indicates that a drug used for treating a form of Leukemia could aid in slowing down the progression of ADPKD.

The drug is called Bosutinib and it acts as a tyrosine kinase inhibitor. In a completed Phase 2 study with 172 enrolled ADPKD patients, Bosutinib effectively reduced the rate of kidney growth (total kidney volume) by 66% for those patients receiving a dosage of 200mg a day. This means that TKV increased on average by 1.63% for this group of patients, as opposed to a standard 4.74% for the placebo group (also representative of what we’d expect in ADPKD patients generally, more or less)

Interestingly, study participants appear to have been originally placed into 3 groups – those receiving 200mg of Bosutinib a day, those receiving 400mg a day, and of course the placebo control group. A “protocol amendment” resulted in the 400mg/day group being dose-reduced to 200mg a day. The reasoning is not particularly clear as to why (find the link to the study at the bottom of this post) especially considering that the reduction in the increase of TKV was even better at the higher dose. It may be due to the adverse side effects of what looks to be a pretty powerful cancer-fighting drug. Common side effects seemed to be gastrointestinal/diarrhea.

Now for a few details that unfortunately don’t make much sense:

  1. According to, this clinical trial started in December 2010, and had a primary completion date of July 2014. Why has it taken more than 3 years for the results of the trial to be made public? The answer may be in point 2 below.
  2. The clinical trial was sponsored by Pfizer Inc. and as of the 2017 Pfizer Pipeline, the Bosutinib treatment for Polycystic Kidney Disease is no longer included in the pipeline of planned projects.

The news of this drug is great, and it looks like the results are fantastic when compared directly to the only other approved PKD drug on the market – Tolvaptan (which slows kidney growth by just on 50%)

Further, it’s not clear whether or not Bosutinib for ADPKD will proceed to a Phase 3 trial or not. If it does, it looks like it’ll be without a corporate sponsor. The news was good to read, but what good is the news if nothing will come of it? Maybe the people involved are hoping that by publishing the results, renewed interest in the treatment will be found, and it can be brought closer to reality. Maybe the side-effects were too great for it to get through another round of trials? I really hope that at some point some of these questions can be answered.

Clinical Trial detail:


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