Gene therapy with hematopoietic stem and progenitor cell for monogenic disorders: a systematic review and meta-analysis

Abstract To provide an assessment of the safety of ex-vivo gene therapy (GT) with hematopoietic stem and progenitor cells (HSPC), we reviewed in a systematic manner the literature on monogenic diseases to describe survival, genotoxicity and engraftment of gene corrected HSPC, across vector platforms and diseases. From 1995 to 2020, 55 trials for 14 diseases met inclusion criteria and 406 patients with primary immunodeficiencies (55.2%), metabolic diseases (17.0%), haemoglobinopathies (24.4%) and bone marrow failures (3.4%) were treated with gammaretroviral vector (γRV) (29.1%), self-inactivating γRV (2.2%) or lentiviral vectors (LV) (68.7%). The pooled overall incidence rate of death was 0.9 per 100 person-years of observation (PYO) (95%CI = 0.37–2.17). There were 21 genotoxic events out of 1504.02 PYO. All these events occurred in γRV trials (0.99 events per 100 PYO, 95%CI = 0.18–5.43) for primary immunodeficiencies. Pooled rate of engraftment was 86.1% (95%CI = 66.9–95.0%) for γRV and 99.0% (95%CI = 95.1–99.8%) for LV HSPC-GT (p = 0.002). A comprehensive meta-analysis on HSPC-GT showed stable reconstitution of haematopoiesis in most recipients with superior engraftment and safer profile in patients receiving LV-transduced HSPC.