Tetracycline to prevent epidermal growth factor receptor inhibitor-induced skin rashes: results of a placebo-controlled trial from the North Central Cancer Treatment Group (N03CB)

Abstract

Background: Epidermal growth factor receptor (EGFR) inhibitors are effective cancer therapies, but they are reported to cause a rash in >50% of patients. In the current study, the authors examined the use of tetracycline for rash prevention.

Methods: This placebo-controlled, double-blinded trial enrolled patients who were starting cancer treatment with an EGFR inhibitor. Patients could not have had a rash at the time of enrollment. All patients were randomly assigned to receive either tetracycline at a dose of 500 mg orally twice a day for 28 days versus a placebo. Patients were monitored for rash (through monthly physician assessment and weekly patient-reported questionnaires), quality of life (using the SKINDEX-16, a skin-specific quality of life index), and adverse events. Monitoring occurred during the 4-week intervention and then for an additional 4 weeks. The primary objective of the current study was to compare the incidence of rash between the study arms, and the enrollment of 30 patients per arm provided a 90% probability of detecting a 40% difference in incidence with a P value of .05 (2-sided).

Results: A total of 61 evaluable patients were enrolled. The 2 treatment arms were well balanced with regard to baseline characteristics, dropout rates, and rates of discontinuation of the EGFR inhibitor. The incidence of rash was found to be comparable across treatment arms. Physicians reported that 16 patients treated with tetracycline (70%) and 22 patients treated with placebo (76%) developed a rash (P = .61). Tetracycline appears to have lessened the rash severity, although the high dropout rates invite caution when interpreting these findings. By Week 4, physician-reported grade 2 rash (using the National Cancer Institute's Common Terminology Criteria for Adverse Events [version 3.0]) occurred in 17% of tetracycline-treated patients (n = 4 patients) and in 55% of placebo-exposed patients (n = 16 patients) (P = .04). Patients treated with tetracycline reported better scores, as per the SKINDEX-16, on certain quality-of-life parameters such as skin burning or stinging, skin irritation, and being bothered by the persistence/recurrence of a skin condition. Adverse events were found to be comparable across treatment arms.

Conclusions: In the current study, tetracycline was not found to prevent EGFR inhibitor-induced rashes and therefore cannot be clinically recommended for this purpose. However, preliminary observations of diminished rash severity and improved quality of life suggest this antibiotic merits further study.

Figure 1. Consort Diagram

The study arms appeared well balanced for drop outs and other such factors throughout the conduct of the trial.

Figure 2. SKINDEX-16 Itching Scores

Serial SKINDEX-16 scores showed a few favorable effects with tetracycline, including better itching scores by week 4. In this figure the y-axis helps illustrate the percentage change in scores from baseline, and the x-axis shows time and the number of patients being evaluated at each time point. The median percent of baseline present at week 4 was 83% in tetracycline-treated patients and 50% in placebo-exposed patients with the higher median percent being more favorable (p=0.005).