ABSTRACT
New prophylactic approaches are needed to prevent acute graft-versus-host disease (GVHD) after allogeneic
hematopoietic cell transplantation (HCT). Despite prophylaxis with current strategies, 30-70% of recipients still
develop acute GVHD. Development of GVHD is the leading cause of morbidity and non-relapse mortality after
allogeneic HCT, and limits the health-related quality of life (HRQOL) of patients and their ability to return to
activities of daily living. Over the last two decades, our multidisciplinary team has been investigating the use of
histone deacetylase (HDAC) inhibition (vorinostat) to prevent GVHD. In adult patients, we have completed a
first-in-human phase I/II trial in related donor, reduced intensity conditioning allogeneic HCT (NCT00810602),
and a phase II trial in unrelated donor, myeloablative conditioning allogeneic HCT (NCT01790568), both
indicating safety of vorinostat, possible attenuation of GVHD without compromising the beneficial graft versus
leukemia (GVL) effect, and potential neuroprotective effects (NCT02409134). Pediatric patients undergoing
allogeneic HCT may also benefit from vorinostat to prevent GVHD, but have faced barriers of access to this
potentially life-saving therapy. We have already submitted an application and obtained an IND from the FDA to
conduct a phase I/II trial of vorinostat in addition to standard GVHD prophylaxis for pediatric patients
undergoing unrelated donor myeloablative conditioning HCT. The purpose of this grant is to fund the phase I/II
clinical trial of vorinostat in pediatric HCT. The phase I portion of the study will enroll up to 12 subjects aged 3–
21 years and will determine the recommended phase II dose (RP2D) of vorinostat using a 3+3 up-or-down
algorithm. The single-arm phase II portion of the study will enroll an additional 37 subjects to receive vorinostat
at the RP2D and will determine the incidence of grade II-IV acute GVHD at day 100 post-HCT. The objective of
this early phase trial in pediatric HCT is to assess dose, safety, pharmacokinetics, pharmacodynamics, and the
RP2D of vorinostat. Important additional endpoints include correlative laboratory studies, cognitive function,
and patient-reported outcomes of HRQOL. We hypothesize that HDAC inhibition with vorinostat regulates the
inflammatory response of GVHD and will correlate with preserved cognition and HRQOL. This study will enroll
pediatric HCT patients for the following reasons: 1) There is a major unmet need of well-designed GVHD
clinical trials in pediatric HCT that integrate clinical outcomes, biological function, cognitive assessments, and
HRQOL measures; 2) Our previous pre-clinical and clinical data of HDAC inhibition for GVHD prevention in
adult HCT provide biological correlates with relevance for mechanism of action; 3) HDAC inhibition may have
neuroprotective properties and preserve HRQOL after allogeneic HCT, a treatment known to negatively impact
cognitive function, particularly in patients receiving unrelated donor grafts, and potentially most significant in
younger aged patients. Thus, this proposal will provide critical information on the safety, tolerability and
preliminary efficacy of vorinostat in pediatric HCT to inform the development of a future, full-scale trial.