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.