Based on these results, a small clinical trial with 10 CD patients was conducted with the purpose of testing the safety of L. lactis secreting human IL-10.231 Because of the safety concerns of using genetically engineered organisms in humans, the human IL-10 encoding cassette was used to replace a thymidylate synthase gene, essential for the growth of L. lactis, with the purpose of blocking its growth and preventing colonization in the host.230,231 An improvement in disease severity in 8 out of 10 participants encouraged a larger phase-II trial (www.clinicaltrials.gov: NCT00729872). This evidence concerns the gene IL10 and Cowden disease.