In March researchers reported that three of five adult subjects who had acute lymphocytic leukemia (ALL) had been in remission for five months to two years after being treated with genetically modified T cells which attacked cells with CD19 genes on their surface, i.e. all B cells, cancerous or not. The researchers believed that the patients' immune systems would make normal T cells and B cells after a couple of months. They were also given bone marrow. One patient relapsed and died and one died of a blood clot unrelated to the disease.
Following encouraging Phase I trials, in April, researchers announced they were starting Phase II clinical trials (called CUPID2 and SERCA-LVAD) on 250 patients at several hospitals to combat heart disease. The therapy was designed to increase the levels of SERCA2, a protein in heart muscles, improving muscle function. The U.S. Food and Drug Administration (FDA) granted this a breakthrough therapy designation to accelerate the trial and approval process. In 2016, it was reported that no improvement was found from the CUPID 2 trial.
In July researchers reported promising results for six children with two severe hereditary diseases had been treated with a partially deactivated lentivirus to replace a faulty gene and after 7–32 months. Three of the children had metachromatic leukodystrophy, which causes children to lose cognitive and motor skills. The other children had Wiskott–Aldrich syndrome, which leaves them to open to infection, autoimmune diseases, and cancer. Follow up trials with gene therapy on another six children with Wiskott–Aldrich syndrome were also reported as promising.
In October researchers reported that two children born with adenosine deaminase severe combined immunodeficiency disease (ADA-SCID) had been treated with genetically engineered stem cells 18 months previously and that their immune systems were showing signs of full recovery. Another three children were making progress. In 2014, a further 18 children with ADA-SCID were cured by gene therapy. ADA-SCID children have no functioning immune system and are sometimes known as "bubble children".
Also in October researchers reported that they had treated six people with haemophilia in early 2011 using an adeno-associated virus. Over two years later all six were producing clotting factor.