Dr. Greg Riely, medical oncologist from MSKCC, discusses the controversial question of whether patients should continue on an oral EGFR tyrosine kinase inhibitor after progression.

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After patents develop resistance to EGFR tyrosine-kinase inhibitors, such as erlotinib, gefitinib or afatinib, we eventually have to make a change in systemic therapy, and if we’ve gone through our first generation or second generation of EGFR tyrosine-kinase inhibitors, and even potentially after third generation EGFR tyrosine-kinase inhibitors, we have the option of using chemotherapy. Chemotherapy is very effective for patients with EGFR mutant lung cancer, and I think it’s definitely something that patients shouldn’t fear because it does have great activity and we can make it quite tolerable for patients to receive these chemotherapies. 

One critical question comes up, as to whether we should continue EGFR tyrosine-kinase inhibitors after development of resistance when we’re starting chemotherapy. Kind of an obvious statement is that, if the patient has developed resistance, and many of my patients ask me this question — “if I develop resistance, why should I continue an EGFR tyrosine-kinase inhibitor?” I think it’s a good question. When we started thinking about this with our patients, long ago, we did what the standard thing was, which is we stop EGFR tyrosine-kinase inhibitors and move on to chemotherapy. When we look back at some data where we had patients stop EGFR tyrosine-kinase inhibitor, prior to enrolling in a clinical trial, the general washout, this period of the time off-drug, that we call it, was about two weeks, and in that time, we saw about 20% of patients have a significant worsening of their disease course — and when I say significant worsening of their disease course, their symptoms got so bad that they were hospitalized, and some of them even died after stopping EGFR tyrosine-kinase inhibitors.

Now, I say that not to frighten people, but to point out that, often, in patients with EGFR mutant lung cancer, there is still some benefit for continuation of EGFR TKI, and there may be a role for continuing with chemotherapy. Importantly, this has been studied in a randomized fashion, so patients with EGFR mutant lung cancer with resistance to first-generation EGFR tyrosine-kinase inhibitors, were randomized to chemotherapy with an EGFR tyrosine-kinase inhibitor, and there wasn’t a difference in the outcome. So, it wasn’t clear in an overall patient population that it mattered if you continued. So, this data really indicates that it’s okay not to continue EGFR tyrosine-kinase inhibitors. I think the one area that I might disagree is maybe in the initial switch from an EGFR tyrosine-kinase inhibitor to the chemotherapy — it would be reasonable to overlap those so that you’re getting the benefits of the chemotherapy and we’re seeing shrinkage of the chemotherapy before you pull back on the EGFR tyrosine-kinase inhibitor.