Andrea Cercek, MD: The main toxicities that were seen in the study with trifluridine/tipiracil, and, I think, are also seen clinically are fatigue, neutropenia, some nausea, vomiting, and a bit of diarrhea. But the main toxicities that affect patients in clinic and affect management are neutropenia and fatigue.
Zev A. Wainberg, MD: When we face the decision about how to treat patients with refractory metastatic colon cancer with TAS-102, we approach TAS-102 in many ways. We approach it in ways similar to how we would discuss side effects of fluoropyrimidines—talk about the cytopenias and the possibility of fatigue, of course. But, in particular, we want to make sure that the blood counts are monitored safely. So, we sometimes tell them their complete blood count as often as weekly to make sure that they’re on the proper dose of TAS-102.
When you’re on it for a little while and you start to see a safe parameter of neutropenia that you’re comfortable with, or thrombocytopenia, then it becomes an easier thing to manipulate. In many ways, the toxicity profile of TAS-102, for many oncologists, is more comfortable. We’re more used to dealing with cytopenias then some of the other side effects that are induced by other drugs.
Andrea Cercek, MD: In my personal experience, the toxicity of TAS-102 is largely neutropenia, fatigue, and nausea. The latter 2, fatigue and nausea, are quite manageable with antiemetics. If we need to take a brief break, patients usually recover. It’s usually not a major factor that limits the ability to dose or limits the patient’s quality of life. For neutropenia, we have been able to successfully manage patients with dose reductions. Often, patients don’t actually need to stop the drug. But we always have the option, of course, of growth factor support, as well.
Zev A. Wainberg, MD: Usually the dose reductions will be based on the prior count. In the package label for TAS-102, the dose is given as 5 days on, 2 days off. Then 5 days on, 2 days off. At the completion, there’s a 14-day break. So, you have the ability to monitor the blood counts, check the CBC, and use those as dosing strategies for subsequent cycles.
If other side effects are being induced, including fatigue or intolerable side effects that can occur, the dosing strategy usually involves dropping to 1 pill at a time to get them down to a dose level that is also sustainable.
Transcript Edited for Clarity