FDA OKs Fidaxomicin Oral Suspension, Tablets for Pediatric C. Difficile

Officials with the FDA have approved fidaxomicin (Dificid, Merck) oral suspension and tablets for the treatment of Clostridioides difficile-associated diarrhea (CDAD) in children aged 6 months and older, according to a press release.

Approval of its new formulation and pediatric indication is based on data from the phase 3 SUNSHINE study, which evaluated the safety and efficacy of fidaxomicin in children aged 6 months to less than 18 years of age.

The study included 148 patients with confirmed CDI, of whom 142 received either fidaxomicin (suspension or tablets, twice daily) or vancomycin (suspension or tablets, 4 times daily). Patients were randomized by age: 30 patients from 6 months to <2 years, 49 patients aged 2 to <6 years, 40 patients aged 6 to <12 years, and 29 patients aged 12 to <18 years.

The results showed that CDAD clinical response in the overall pediatric population, assessed through 2 days following 10 days of treatment, was similar between the fidaxomicin and vancomycin groups (77.6% versus 70.5% with a 95% CI for the treatment difference of 7.5 [-7.4%, 23.9%]). Additionally, sustained clinical response, which was defined as the proportion of treated patients with confirmed clinical response and no CDAD recurrence through 30 days after the end of treatment, was higher in the fidaxomicin group than for vancomycin (68.4% versus 50% with a 95% CI for the treatment difference of 18.4 (1.5%, 35.3%]).

A phase 2 single-arm study of 38 pediatric patients and a phase 3 study of 98 pediatric patients treated with fidaxomicin and 44 patients treated with vancomycin evaluated the treatment’s safety profile. Treatment discontinuation due to adverse effects occurred in 7.9% of patients in the phase 2 study and in 1% and 2.3% of in fidaxomicin- and vancomycin-treated patients, respectively, in the phase 3 trial. In patients treated with fidaxomicin in the phase 3 trial, the most common adverse effects were pyrexia, abdominal pain, vomiting, diarrhea, constipation, increased aminotransferase, and rash. One death occurred in the phase 2 study and 3 deaths occurred in the phase 3 study, all of which occurred in patients less than 2 years of age and appeared to be related to underlying comorbidities, according to the press release.

“C. difficile is an importance cause of health care- and community-associated diarrheal illness in children, and sustained cure is difficult to achieve in some patients,” Larry K. Kociolek, MD, MSCI, associate medical director of Infection Prevention and Control at Ann & Robert H. Lurie Children’s Hospital of Chicago, said in a statement. “The fidaxomicin pediatric trial was the first randomized controlled trial of C. difficile infection treatment in children. I am very excited to have a new C. difficile infection treatment option for my pediatric patients.”

References:

• FDA Approves Merck’s DIFICID (fidaxomicin) to Treat Clostridioides difficile in Children Aged 6 Months and Older [news release]. Merck’s website. https://www.mrknewsroom.com/news-release/prescription-medicine-news/fda-approves-mercks-dificid-fidaxomicin-treat-clostridioides. Accessed January 27, 2020.