FDA Guidance on Drug Development for DFIs
In October, the FDA issued draft guidance for industry to articulate the design of clinical trials for developing antibacterial drugs to treat DFIs without concomitant bone and joint involvement. Comments closed on December 18. Among the points in the guidance, which is nonbinding, are to include DFIs of varying depths and extent in phase 3 trials and ideally to include only those patients who have not had prior antibacterial treatment for the current DFI.
According to an FDA spokesperson, “The agency is working to finalize the guidance. However, a timeline for its release has not yet been established.”
The good news about the upcoming FDA guidance, Dr. Armstrong said, is that the agency has realized the importance of treating the infections. Fully one third of direct costs of care for diabetes are spent on the lower extremities, he said. Keeping patients out of the hospital, uninfected, and “keeping legs on bodies” are all important goals, he said.
Pharmaceutical firms need to understand that “you aren’t dealing with a normal ulcer,” said Andrew J.M. Boulton, MD, professor of medicine at the University of Manchester and physician consultant at the Manchester Royal Infirmary, Manchester, England, and a visiting professor at the University of Miami. For research, “the most important thing is to take account of off-loading the ulcers,” he said. “Most ulcers will heal if put in a boot.”
Dr. Boulton, like Dr. Armstrong, a long-time expert in the field, contended that pharma has not understood this concept and has wasted millions over the last three decades doing studies that were poorly designed and controlled.
Treatments: Current, Under Study
Currently, DFIs are treated with antimicrobial therapy, without or without debridement, along with a clinical assessment for ischemia. If ischemia is found, care progresses to wound care and off-loading devices, such as healing sandals. Clinicians then assess the likelihood of improved outcomes with revascularization based on operative risks and distribution of lower extremity artery disease and proceed depending on the likelihood. If osteomyelitis testing shows it is present, providers proceed to wound debridement, limb-sparing amputation, and prolonged antimicrobials, as needed.
More options are needed, Dr. Armstrong said.
Among the many approaches under study:
- DFUs can be accurately detected by applying artificial intelligence to the “foot selfie” images taken by patients on smartphones, research by Dr. and has found.
- After a phase 3 study of for DFUs originally intending to enroll 300 subjects was discontinued because of slow patient recruitment, an interim analysis was conducted on 44 participants. It showed a positive trend toward wound closure in the group receiving the injected gene therapy, VM202 (ENGENSIS), in their calf muscles. VM202 is a plasmid DNA-encoding human hepatocyte growth factor. While those in both the intervention and placebo groups showed wound-closing effects at month 6, in 23 patients with neuro-ischemic ulcers, the percentage of those reaching complete closure of the DFU was significantly higher in the treated group at months 3, 4, and 5 (P = .0391, .0391, and .0361, respectively). After excluding two outliers, the difference in months 3-6 became more significant (P = .03).
- An closed more DFUs than standard care after 12 weeks — 70% vs 34% (P = .00032). Of the 100 participants randomized, 50 per group, 42% of the treatment group and 56% of the control group experienced adverse events, with eight withdrawn due to serious adverse events (such as osteomyelitis).
- A closed more refractory DFUs over a 16-week study than standard sharp debridement, with 65% of water-treated ulcers healed but just 42% of the standard care group (P = .021, unadjusted).
- Researchers from UC Davis and VA Northern California Healthcare are evaluating timolol, a beta adrenergic receptor blocker already approved for topical administration for glaucoma, as a way to heal chronic DFUs faster. After demonstrating that the medication worked in animal models, researchers then launched a study to use it off-label for DFUs. While data are still being analyzed, researcher Roslyn (Rivkah) Isseroff, MD, of UC Davis and VA, said that data so far demonstrate that the timolol reduced transepidermal water loss in the healed wounds, and that is linked with a decrease in re-ulceration.