Prescriber adherence to antiemetic guidelines with the new agent trifluridine-tipiracil

Cancer drugs are becoming available at an unprecedented rate. In 2015 alone, the US Food and Drug Administration (FDA) approved 18 new agents.¹ Although many of those agents have adverse event profiles that are more favorable than those seen with conventional chemotherapy, nausea and vomiting still occur. In fact, nausea and vomiting continue to be ranked as among the most common and distressing of cancer symptoms.^2,3 In a 2004 study, Grunberg and colleagues reported that as many as 75% of health care providers misjudge the risk for chemotherapy-induced nausea and vomiting (CINV), even when prescribing cancer drugs that have been available for years,⁴ thus amplifying concerns that such risk assessment might be even worse when new cancer agents are prescribed for the first time.

In this study, we hypothesized that patients prescribed a new cancer drug, trifluridine-tipiracil, would be at risk for CINV because of poor guideline adherence on the part of health care providers. The correct matching of antiemetics to chemotherapy is important. Inadequate antiemetic prophylaxis predisposes to nausea and vomiting with dehydration and metabolic and electrolyte derangements – complications that can occur in up to one-third of patients who receive moderately or highly emetogenic chemotherapy and who have been reported to achieve poor symptom control.⁴ Over-prophylaxis also has drawbacks. For example, antiemetics are expensive and, at times, they can induce their own adverse events, such as lethargy, dyskinesia, constipation, headaches, hiccups, fatigue, and even cardiac arrhythmias.⁵ The best approach is to appropriately match the antiemetic to the chemotherapy. Indeed, adherence to evidence-based guidelines has yielded success in symptom control, but the guidelines work on the assumption that the emetogenic potential of new chemotherapy agents has been accurately determined and then disseminated to and acted upon by health care providers.^6,7 To our knowledge, no previous studies have tested that assumption, as we do in the present study.

Trifluridine-tipiracil was selected as the focus of this project and as illustrative of other newly approved chemotherapy agents for two reasons. First, it became available for routine prescribing in pretreated patients with metastatic colorectal cancer in the United States in September 2015.¹ That timing allowed us to analyze much of the early prescribing period, both during the 9 months before approval, when the drug was available on a compassionate-use basis at our institution, and the 3 months after approval. Second, trifluridine-tipiracil has classifiably low emetogenic potential, and mismatching of antiemetics tends to occur more often with low emetogenic chemotherapy.⁹ Trifluridine-tipiracil and placebo patients manifest rates of nausea at 48% and 24%, respectively, and rates of vomiting at 28% and 14%, respectively.⁸

Hence, the goal of this study was to explore whether a guideline-based prophylactic antiemetic regimen was appropriately matched to the new chemotherapy agent, trifluridine-tipiracil, to report whether such symptoms of nausea and vomiting are kept at bay, and to identify a potentially vulnerable interval – immediately after drug approval – when cancer patients may be at risk for CINV because of poor adherence to antiemetic guideline prescribing practices by health care providers.

Methods

Overview

The Mayo Clinic Institutional Review Board approved this study. We obtained the identifying information of all patients treated with trifluridine-tipiracil at our institution from the Mayo Clinic Specialty Pharmacy, which uses an electronic prescribing system that contributed to the comprehensiveness of the data set. Patients included those who had participated in a colorectal cancer compassionate-use program before the September 2015 approval of the drug and those who received the drug shortly after its approval. In essence, this retrospective, single-institution study included every patient who received trifluridine-tipiracil for metastatic colorectal cancer in 2015 (January through December); this approach enabled us to systematically report on early first-cycle prescribing practices 9 months before and 3 months after the drug’s approval in September of 2015.

Determination of guideline adherence

This project relied on the National Comprehensive Cancer Network (NCCN) Guidelines (v1.2015, behind paywall) because they had been updated in 2015 (and hence coincided with this project’s study dates) to incorporate recommendations specific to oral chemotherapy and because they seemed concordant with other guidelines.^10,11

Antiemetic prophylaxis for a specific patient was deemed guideline adherent if a version of the recommended NCCN antiemetic regimen had been prescribed during the first cycle of chemotherapy. This regimen consisted of metoclopramide, prochlorperazine, haloperidol, or a 5-hydroxytryptamine receptor antagonist. In contrast, if a patient had been prescribed a more aggressive or less aggressive regimen, such prescribing practices were deemed non–guideline adherent/aggressive (received more prophylaxis than called for) or non–guideline adherent/less aggressive (including no antiemetics), respectively. Again, medical record prescribing determined adherence.