Figure 5. T cell reconstitution in patients after cell therapy.

P1, a child with Fanconi anaemia, underwent a second mismatched donor, CD34 selected stem cell graft after in the context of relapsed MDS. Donor HSVTK/CD34 modified T cells were infused in two dose aliquots and were detectable at low level in peripheral blood for over 12 weeks before the patient died of disease relapse. The persistence of non-modified T cells reflects the reduced intensity conditioning and absence of serotherapy. P2, an infant with RAG1 deficient SCID had no pre-existing T cell immunity and was conditioned whist infected with H1N1 influenza. Modified T cells persisted for over 12 months, with eventual recovery of thymic derived donor T cells after one year and normalisation of immunity. P3 suffered Ligase IV deficiency, a form of radiosensitive SCID. Expansion of modified donor T cells was detected within two weeks of first infusion, but the patient died from mucositis related pulmonary and gastrointestinal haemorrhage before dose escalation.