The proportion of patients who had complete healing by week 12 was 46 percent in the control groups versus 70 percent in patients who received cells every 14 days. The other active-therapy groups also had higher rates of complete healing compared with the control group, but the differences did not reach statistical significance.
The most effective dose of HP802-247 achieved wound closure in an average of 50 days versus 71 days in the control group. Comparison of healing rates showed that patients treated with the most effective dose of the spray-on cells had an 83 percent greater likelihood of wound healing compared with the patients who received vehicle only.
Adverse event rates did not differ significantly across treatment groups. The only events that occurred in more than 5 percent of patients were new skin ulcers and cellulitis.
The ability to specify a dose, frequency, and duration of treatment is a key distinguishing feature of the spray-on cells compared with other tissue-based treatments for venous leg ulcers, Dr. Matthias Augustin of the University of Hamburg and Dr. Wolfgang Vanscheidt of Dermatologische Praxisgemeinschafts in Freiberg, Germany wrote in an accompanying commentary.
The costly nature of tissue-based therapies requires careful evaluation to determine the most cost-effective use of the therapies.
"The questions of which products best promote healing and which products fail to increase healing rates of previously nonhealing ulcers need to be answered and are essential to address cost-effectiveness," they wrote.
"In these wounds, prolonged futile, conservative treatment will increase costs without additional benefit. Therefore, the temporary higher costs for additional cell and tissue-engineered therapy can be justified as an investment in improved healing."