Original post is on The ROS1ders website

I’m Janet Freeman-Daily, a cofounder of The ROS1ders.  I’m writing this post in response to some of the comments we’ve seen recently in our private Facebook group “ROS1 Positive (ROS1+) Cancer.”

Many of our members who have ROS1+ cancers take the targeted therapy crizotinib (Xalkori), a tyrosine kinase inhibitor (TKI).  It was approved by the US FDA for ALK+ non-small cell lung cancer (NSCLC) in 2011, and for ROS1+ NSCLC in 2016.

Many ALK+ and ROS1+ NSCLC patients have had long-term stability or no evidence of disease (NED) on crizotinib, and are tolerating it well. Some of these patients suggested they might “take a vacation” from crizotinib for a while, as some people do with chemo. They think this could help them avoid developing resistance to crizotinib (which could allow them to stay on the drug longer), and that they can start taking the drug again later if the cancer returns. Their oncologist might even agree with this idea.  But …

PLEASE — If crizotinib (Xalkori) is working for you and you can tolerate it, consult a ROS1 expert before stopping treatment!  

If your doctor tells you should stop taking crizotinib for a medical reason (like a severe side effect or toxicity), or temporarily during surgery or radiation, you should follow their advice. But don’t stop taking crizotinib just because you want a drug vacation.

ROS1+ cancer is a rare disease. Oncologists who have seen no or few ROS1 patients usually haven’t followed the fast-moving research into this disease.

Dr. Ross Camidge and Dr Robert Doebeleare among a handful of doctors who have treated dozens of ROS1+ and ALK+ patients with crizotinib. Globally, they are considered experts in ROS1+ NSCLC.  Both have told me they think it’s a bad idea for patients to stop taking Xalkori just because they’re NED or stable on the drug. Below are the reasons they gave me.

• Targeted therapies are not the same as chemo. TKIs inhibit the cancer, but do not kill it. For metastatic cancer patients, cancer cells likely remain in the blood, lymphatic system, or body (we just don’t have the means to detect them–that’s why we say “no evidence of disease” instead of “cancer free”).  If you stop treatment, you stop inhibiting those cancer cells, and any cancer that remains can resume growing—sometimes very fast. Those cells can continue to mutate. There is no guarantee that crizotinib will be effective against your cancer when you restart it after a “drug vacation.”
• TKI flare is well documented for EGFR and ALK patients on TKIs like Xalkori.  What is TKI flare? Some patients (not all) on TKIs who stop taking the drug can see their cancer grow quickly after just a week or two. When they restart the drug, it doesn’t always work again.
• We don’t have much evidence of what may happen if NED patients stop taking their TKI, except for one study.  In the study,  EGFR+ NSCLC patients who had no evidence of disease on Tarceva (a TKI like Xalkori) stopped taking their cancer drug. All saw their cancer return within a year.
• While chronic myeloid leukemia (CML) patients on a TKI (Gleevec) have been able to stop taking their TKI, their blood cancer is not as aggressive and deadly as lung cancer.

Each patient has the right to make up their own mind about their treatment,  In my case, I have had no evidence of disease on crizotinib for 6 years. When I asked about stopping crizotinib, Dr. Camidge has told me that he does not want me to stop taking my cancer drug. I’m going with his expert opinion.