Inclusion Criteria:

- Patients with any NIH subtype of chronic GVHD that is being treated with ECP

- Karnofsky Performance Scale (KPS) > 60% at time of study enrollment

- Life expectancy > 3 months

- Steroid dose not greater than 2 mg/kg prednisone equivalent at time of study
enrollment

- If patient has steroid refractory GVHD (defined as worsening of GVHD after 3 days of
2 mg/kg prednisone equivalent or no improvement after 7 days of 2 mg/kg prednisone
equivalent), time interval from start of steroids to initiation of ECP should not be
> 14 days

- No use of an investigational agent within 2 weeks of starting ECP

- No uncontrolled bacterial, fungal or viral disease (therapy for cytomegalovirus [CMV]
viremia is permitted)

- No evidence of relapse or progression of underlying disease (molecular evidence of
relapse/progression or mixed chimerism is permitted)

- Women of childbearing potential (WOCBP) should be willing to use 2 forms of
contraception; male patients should be willing to use contraception

- Voluntary written informed consent before performance of any study-related procedure
not part of normal medical care, with the understanding that consent may be withdrawn
by the subject at any time without prejudice to future medical care

Exclusion Criteria:

- Female patients who are breastfeeding or pregnant

- Patients known to be human immunodeficiency virus (HIV) positive

- Bronchiolitis obliterans as the sole indication of ECP

- Serious medical or psychiatric illness likely to interfere with participation in this
clinical study

- Mechanical ventilation, renal replacement therapy, admitted in intensive care until
at time of enrollment

- Stage 4 gastrointestinal GVHD as per Seattle-Glucksberg criteria