A phase 2 study for evaluating doxycycline 50 mg once daily and 100 mg once daily as preemptive treatment for skin toxicity in patients with metastatic colorectal cancer treated with an anti-EGFR and chemotherapy.

purposeTo assess the efficacy, safety, and quality-of-life outcomes of doxycycline 50 or 100 mg once daily in the prevention of skin toxicity in patients undergoing chemotherapy plus anti-EGFR therapy as first-line treatment of metastatic colorectal cancer (mCRC).

methodsPhase II, multicenter, single-arm, exploratory study was conducted in 7 Spanish hospitals. The primary study outcome was the incidence of ≥ grade 2 skin toxicities during the 6-week skin treatment period. Quality of life was assessed with the Dermatology Life Quality Index (DLQI) questionnaire. Patients had to receive either doxycycline 50 mg once daily in a first stage with 10 patients, or, if more than three patients presented ≥ grade 2 skin toxicities, the next 30 patients had to receive 100 mg once daily.

resultsThirty-four patients with RAS wild-type mCRC were enrolled in the study. Ten patients were first treated with doxycycline 50 mg once daily, and the following 24 were treated with doxycycline 100 mg once daily. A total of 60.0% (95% CI 29.6-90.0) and 20.8% (95% CI 4.6-37.0) of patients who received doxycycline 50 mg/day and 100 mg/day, respectively, had at least one ≥ grade 2 skin toxicity. Patients treated with doxycycline 100 mg once daily experienced less QoL deterioration. Only 1 patient reported a mild doxycycline-related gastrointestinal adverse event.

conclusionOur results suggest that doxycycline doses as low as 100 mg once daily are efficacious and well tolerated for the prevention of skin toxicity in patients with mCRC who undergo treatment with chemotherapy plus EGFR-targeted therapies.

trial registrationClinicalTrials.gov NCT03448731.