CDK4-6 Trial


The appointment yesterday was anything but resolving. More uncertain questions, followed by unclear answers. We are now being told, by yet another doctor, that Avastin may not be the hopeful drug we had hoped it would be. All of our hopes for this drug for the past 6 months have been shattered again. Imagine holding hope that a drug was going to give you more time with your sweet, beautiful, warm, loving, child… and finding out that it may have done nothing at all. According to another doctor, Avastin does work, but doesn’t always work in every patient. “Her tumor is growing, that tells you something. ” he said… Now what do we do? According to Katie’s Oncologist, she has taken a patient off of Avastin and he declined sooner than 2 weeks. His parents didn’t even get two weeks and didn’t make it to trial. How devastating. I’m angry again. I’m trying to not be bitter. And I thought I knew what tough decisions were prior to Katie’s diagnosis. We hold our child’s life our my hands. Daily. Well, we always did, but now it’s on paper. A paper we have to sign in triplicate. Oh, and if she passes, we will have to sign that paper too.

This “hopeful” trial at CHLA is called PBTC-042/CDK4-6/PD-0332991. It would only require that Katie not be off Avastin for 3 weeks. Scary. The other was 6, and you can guess our answer to that one… She would need to be off Panobinostat, for two. Doable. A brief definition: “Tumor cells grow and divide rapidly and uncontrollably. In normal cells, specific proteins and their enzymes called cyclin dependent kinases (CDK4 and 6) tightly control the process of cell division. Another protein called Rb1 also regulates this cell division and stops the cells from dividing. This Rb1 protein suppresses tumor formation in normal cells. But in cancer, the two kinases (CDK4 and 6) are out of control and drive the cell to divide and form cancer. Tumor cells can sometimes transform or inactivate Rb1 to help them divide continuously. In this study, we are testing an experimental drug called PD-00222991 (called Palbociclib) that works by inhibiting the CDK4 and 6 proteins. In animal studies, researchers have found that this drug works only if tumor cells have an intact Rb1 protein. Over 60 percent of brain tumors in children are likely to have an intact Rb1 protein. You have approached for this study because tumor has been identified to have an intact Rb1 protein”

Not one DIPG patient is on this trial. We would be the first at CHLA. And we don’t know if Katie has this Rb1 protein. We can’t biopsy, so we stab in the dark, and hope. Katherine King’s life is dependent on a drug that we don’t know will work, but is promising, in the petri dish and in lab mice. We have to stop all other drugs, that may, or may not be working, to take this hopeful drug that may, or may not work as well, and hasn’t been tested on any other pediatric patients. The sad look on the doctors face is familiar, yet stark, every time.

That is all I have, and could possibly bear, for today. But no matter what, I wanted to update you all. You all have done so much for Katherine and us, and you deserve an update.

Thank you…

– mom


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