Phase II Trial of Natalizumab (Tysabri®) Plus Prednisone for Initial Therapy of Acute Graft Versus Host Disease (aGVHD) of the Gastrointestinal Tract

Natalizumab is a drug that was initially discovered as a treatment for autoimmune conditions.
Natalizumab has been approved for use in patients with Multiple Sclerosis and Crohn's
disease. In these diseases, the drug works to inhibit dysfunctional immune cells that are
responsible for the symptoms seen in these diseases. Acute graft versus host disease is
caused by a similar dysfunction of immune cells; Natalizumab is thought to inhibit these
immune cells, similarly to how it does in Multiple Sclerosis and Crohn's disease. In this
research study,the investigators are looking to see whether Natalizumab provides additional
benefit to patients receiving standard treatment for acute graft versus host disease of the
gastrointestinal tract.

Participants who fulfill eligibility criteria will be entered into the trial to receive
Natalizumab.

- Participant will receive a dose of the natalizumab through intravenous infusion.
Participants may receive a second dose at Day 28 if they experience a partial response
or very good partial response.

- Scheduled Physical Examination at screening, during the week of first dose and at 28
days, 56 days, 100 days, 180 days and one year.

Inclusion Criteria:

- Participants must meet the following criteria on screening examination to be eligible
to participate in the study:

- Participants must have acute GVHD of the lower gastrointestinal tract as defined by
the clinical impression of the treating physician, requiring systemic treatment.
Minimum criteria for GI GVHD includes diarrhea of greater than 500 mL/day. Biopsy of
the GI tract is required for study entry and must confirm the diagnosis of acute GVHD.
Stool samples to rule out infectious causes of diarrhea, including norovirus,
Clostridium difficile and other clinically indicated infections must also be negative.
Eligibility includes:

- Acute GVHD developing after allogeneic hematopoietic stem cell transplantation
(HSCT) using bone marrow, peripheral blood stem cells, or umbilical cord blood.
Recipients of non-myeloablative, reduced intensity and myeloablative transplants
are eligible.

- Patients who develop acute GVHD after donor lymphocyte infusion (DLI) are
eligible.

- There is no specified time window after day 0 of transplant as acute GVHD is only
defined by clinical manifestations.

- Patients must have experienced neutrophil engraftment after HSCT as defined by
absolute neutrophil counts ≥ 500 / µL × 3 consecutive measurements. Absolute
neutrophil count (ANC) should be calculated using the standard formula (Neut +
Bands)(WBC × 101).

- The presence of hepatic, upper GI and/or cutaneous acute GVHD is permitted.

- Steroids can be started up to 7 days prior to the administration of natalizumab.

- Age ≥ 18

- Ability to understand and the willingness to sign a written informed consent document.

Exclusion Criteria

- Participants who exhibit any of the following conditions at screening will not be
eligible for admission into the study:

- Patients with the entity of Acute/Chronic GVHD overlap syndromes.

- Requiring mechanical ventilation

- Vasopressor requirement

- Concurrent hepatic veno-occlusive disease (VOD) based on clinical examination

- Karnofsky performance status < 30

- Participants may not be receiving any other study agents for at least 7 days prior to
enrollment

- Prior use of natalizumab for any reason is not allowed

- Pregnant women are excluded from this study because of the potential teratogenic
effects of natalizumab. Because natalizumab enters breast milk, and the effect is
unknown in infants, breastfeeding should be discontinued if the mother is treated with
natalizumab.