I started Alectinib May 20 and I am scheduled for a brain MRI this Friday June 17th. Will this be appropriate timing to see if Alectinib will have an effect on my brain mets or should I push back my brain MRI? I had 20 small brain mets showing on my last two MRI (Nov 2015 and March 2016) while on Ceritinib.
Hi ownit, thanks for the question. Most patients with known brain metastases get surveillance MRI scans periodically, and it appears you are on a 3 month interval which is very common. It is generally a good idea to keep on a somewhat regular schedule so you don’t miss changes that can be addressed with a change in treatment or perhaps radiation, but the exact time of 3 months isn’t that critical.
No one knows the best time to look for response to a drug like alectinib, but most clinical trials use 6 or 8 week intervals for scans to keep the endpoints like “progression free survival” the same between trials and so in practice we end up copying this. In reality though, drugs like alectinib can start to work within days, and often responses can be seen within a week or two. I think an MRI 5 weeks after starting alectinib has a good chance of accurately reflecting whether the tumors are going to respond, but if they were stable they could certainly still shrink on the next scan. I don’t think waiting longer is likely make much of a difference since both stable and shrinking are good.
Nathan Pennell, MD
Associate Professor, Solid Tumor Oncology
Cleveland Clinic Taussig Cancer Center
Views expressed here represent my opinion, not those of GRACE or Cleveland Clinic Taussig Cancer Center. This information does not constitute medical advice and is intended to supplement and not replace medical information provided by your doctor.