INTRODUCTION:
Primary immune deficiencies (PID) are a group of over 400 rare congenital diseases with increased susceptibility to infection, autoimmunity, inflammation, cancer and atopy (1); some of which are amenable to hematopoietic stem-cell transplantation (HSCT). Since 1968 (2), those PID patients with genetic variants that affect T cell function, or with a strong hematopoietic component (3) that confer a long-life risk for overwhelming infection, autoimmunity and cancer (4), are recognized as good candidates for allogeneic HSCT.
During the last couple of decades, the prognosis for patients with PID who undergo HSCT has greatly improved, thanks to the shared experience of multiple centers around the globe, leading the way in the generation of insights and implementing advances that have become the standard of care (5,6). Early age, identical matched donor, and active infection-free status are three main protective factors that impact survival (7). The rates of graft-versus-host disease (GVHD) in the first 12 months of transplantation with mobilized blood stem-cells from peripheral blood can be as high as 35-50% with conventional chemotherapy regimens. Ideally, T cell-depleted grafts from HLA-identical donors are preferred.
For many patients, HSCT may be lifesaving and curative. However, on the road to transplant there is a series of obstacles and hurdles for providers and patients to overcome, starting with the search for a compatible donor, getting to day zero without an active infection, achieving engraftment, sustaining donor chimerism, preventing complications like rejection, viral reactivation, GVHD, post-transplant lymphoproliferative disease (PTLD), or fatal infection before immune reconstitution. Successful transplant, uneventful recovery or even survival are never assured. Nevertheless, every hospital must start at some point and endure their own lengthy learning curve before reaching optimal results.