A wound spray built from two of the oldest antibacterial molecules in biology just posted its first controlled result in diabetic foot ulcers, and the honest read is split. The ulcers got better. The bug counts, mostly, did not.
The drug is peceleganan, sold in China as PL-5. It is an antimicrobial peptide, a short engineered protein fragment that kills bacteria by tearing holes in their outer membrane rather than jamming a single enzyme the way most antibiotics do. Peceleganan is a lab-made hybrid of two natural killers: cecropin, from the immune system of moths, and melittin, the main toxin in bee venom. Developed by ProteLight Pharmaceuticals with Sino Biopharmaceutical's Chia Tai Tianqing unit, it was cleared in June 2026 by China's National Medical Products Administration as a first-in-class innovative drug for infected burn wounds. In an earlier phase 2b trial in Annals of Surgery ↗, the spray cleared infection in 96 to 100 percent of patients across dose groups, beating the 87.5 percent seen with the old standard, silver sulfadiazine cream.
Diabetic foot ulcers are a harder target. They are chronic, poorly perfused, and colonized by mixed and often drug-resistant flora that sit inside biofilm, the slime layer bacteria build to shrug off both antibiotics and the immune system. That is the setting for the new trial, published in the Journal of Diabetes ↗ by a group running four tertiary hospitals. It was double-blind and placebo-controlled, the strongest design a wound drug can carry. Every patient got standardized debridement, the surgical cleaning of dead tissue that is the real backbone of ulcer care, and then either peceleganan spray or a placebo spray on top.
Clinical better, microbiological a wash
On the trial's main measure, the clinical response rate one day after treatment ended, the peceleganan group did significantly better than placebo. The abstract reports the gap as statistically real (p less than 0.05) without printing the two rates, so the size of the clinical win is not yet public. That matters, because the microbiology told a flatter story. Overall, the share of patients whose infecting bacteria were fully eradicated did not differ between the groups in a statistically meaningful way: 57.9 percent on peceleganan versus 33.3 percent on placebo right after treatment, and 64.7 versus 40.0 percent a week later, both differences inside the range that could be chance at this sample size.
So the drug made ulcers look and behave better without clearing measurably more bacteria overall. That is not a contradiction so much as a reminder that in a chronic wound, reducing the bacterial burden and calming the local infection are not the same axis, and clinical scoring can move before a culture goes fully negative.
The one place the bug counts did move is the place that matters most for a membrane-disrupting peptide. Among patients carrying drug-resistant bacteria, peceleganan cleared the resistant organisms in 71.4 percent of cases versus 50.0 percent on placebo, a significant edge. A peptide that punches the membrane does not care whether the target has an efflux pump or a beta-lactamase, the two tricks that let bacteria defeat conventional drugs. Peceleganan is documented to kill methicillin-resistant Staphylococcus aureus (MRSA) and drug-resistant Acinetobacter baumannii, two of the harder pathogens in chronic wounds, which is exactly why the resistant subgroup is where an antimicrobial peptide should pull ahead. Side effects were no worse than placebo (24.2 versus 33.3 percent) with no serious drug-related events, consistent with the burn data showing the peptide stays on the wound and does not reach the bloodstream.
Why the resistant signal is the story
Read cautiously, this is a modest trial with a real but narrow win: a clinical benefit whose exact magnitude is not yet reported, no overall microbiological superiority, and a resistant-subgroup clearance advantage that will need a larger, powered study to confirm. Read generously, it is the first placebo-controlled hint that an approved antimicrobial peptide can do useful work in the resistant infections where the antibiotic pipeline is thinnest.
That is the same thesis peptidemodel has tracked from the research side. The antimicrobial target ↗ hosts roughly 300 candidate cards, most of them still preclinical, including designed peptides meant to revive defeated antibiotics rather than replace them. Peceleganan is the rarer thing: a membrane-active peptide already approved and now being pushed, one careful indication at a time, into the wound-healing ↗ problems where resistance has left the fewest options.