Allogeneic Virus-specific T Cell Lines (VSTs)

Investigators evaluated the clinical utility of Multivirus VSTs in recipients of matched
related, matched unrelated, or haploidentical donor transplants. To date, 10 clinical-grade
multivirus-directed VSTs have been generated from donor PBMCs. These lines were polyclonal,
comprising both CD4+ (57±5%) and CD8+ (35±5%) cells and retained expression of the memory
markers CD45RO+CD62L+ (58±8%). Their specificity was dependent on the prior viral exposure of
the cell donor; 7/8 tested lines had activity against Adv,8/8 against CMV, 6/8 against EBV.
None of the lines reacted against recipient PHA blasts - indicating lack of alloreactive
potential in these rapidly generated lines.

Investigators administered these multivirus-specific donor-derived VSTs to 3 allogeneic HSCT
recipients in a dose escalation study all on DL1 (5x106/m2). There were no immediate infusion
toxicities, and no de novo acute GvHD, demonstrating the in vivo safety of these mVST.
Further, antiviral efficacy has been observed in 1 patient with refractory CMV. In addition,
in a recently published paper from Baylor College of Medicien (Anapoulous et al, STM 2014)
they have treated VSTs manufactured with a similar methodology, but targeting 5 viruses
instead of 3 with specificity to BK virus and HHV6. In that study 10 patients were treated
with 4 on DL1 (5x10e6/m2), 4 on DL2 (1x10e7/m2) and 2 on DL3 (2x10e7/m2) and again saw no
immediate infusion toxicities, and no de novo acute GvHD, demonstrating the in vivo safety of
these mVST. Three patients received the cells as viral prophylaxis (days 38-43 post-HSCT) and
none developed viral infections at up to 3 months post-treatment. The other 7 patients
received the cells as treatment for one or more active infections between days 59-139
post-HSCT. Based on viral load measurements by day 42 post-infusion, the VSTs were successful
in controlling active infections with CMV (1 complete (CR) and 1 partial response (PR)), EBV
(2 CRs, including a case of frank PTLD); Adv (1 CR); HHV6 (1 CR); and BK (3 CR, 1 PR, 1NR).
Of note, 3 BK virus responders had tissue disease with severe hemorrhagic cystitis and all
had marked improvement or disappearance of hematuria following infusion. One patient
subsequently had an episode of transient but severe bladder pain in association with
inflammation seen on cytoscopy coincident with a 6 log fall in urine BK viral load. Only
non-responder was a patient with BK infection whose line lacked activity for this virus,
likely reflecting the serostatus of the donor. In addition, 3 patients subsequently
reactivated other viruses than those for which they were initially treated, but all cleared
these infections by week 12, without the requirement for additional cell infusions (CMV: 1CR;
EBV: 1CR; BK: 1CR; HHV6: 1CR). Finally, 1 patient received multivirus specific VSTs under a
single patient protocol as an emergency treatment for widespread and bulky
rituximab-resistant EBV-PTLD. Post VST treatment there was an immediate decline in the
patient's EBV viral load with complete and sustained resolution of PTLD, coincident with an
increase in circulating EBV-specific T cells. However, the profound anti-tumor activity
mediated by the rapidly-expanding EBV-directed T cells also produced a transient systemic
inflammatory response syndrome, which was controlled with steroids and anti-TNFR antibody,
with no long term adverse effects.

Thus, infusion of donor-derived, multivirus specific VSTs generated with clinical grade
pepmixes and infused either prophylactically or as treatment for one or more viral infections
has been safe and is associated with the appearance of virus-reactive T cells in peripheral
blood that have been able to control infection with above mentioned viruses.

Inclusion Criteria:

1. Received prior myeloablative or non-myeloablative allogeneic hematopoietic stem cell
transplant using either bone marrow, single/double cord blood or PBSC

2. Cells administered as;

1. Treatment of persistent or relapsed reactivation or infection

2. Early treatment for single or multiple infections with EBV, CMV and/or adenovirus

3. Steroids less or equal to 0.5 mg/kg/day prednisone

5)Bilirubin <3x, AST <3x, Serum creatinine <2x upper limit of normal, Hgb >8.0, plts >20 6)
Pulse oximetry of > 90% on room air 7) Available VSTs 8) Negative pregnancy test (if female
of childbearing potential after reduced intensity conditioning) 9) Patient or
parent/guardian capable of providing informed consent.

Exclusion Criteria:

1. Received ATG, Campath or other T cell immunosuppressive monoclonal antibodies in the
last 28 days.

2. Patients with other uncontrolled infections

3. Received donor lymphocyte infusion in last 28 days

4. Evidence of GVHD > or equal to grade 2

5. Active and uncontrolled relapse of malignancy