Immunotherapy Demonstrates Long-Term Success in Treating Lymphoma

WASHINGTON, Oct. 30 /PRNewswire-USNewswire/ -- Targeted immunotherapy has been
an attractive new therapeutic area for a number of cancers because it has the
potential to destroy tumor cells without damaging surrounding normal tissue.
New study results demonstrate high success rates using specialized white blood
cells to prevent or treat lymphoma associated with the Epstein-Barr virus
(EBV-lymphoma) in patients who have received a hematopoietic stem cell
transplant (HSCT). This study was pre-published online today in Blood, the
official journal of the American Society of Hematology.

Lymphoma is a cancer of white blood cells called lymphocytes that are largely
responsible for maintaining the body's immunity, and EBV is one of the most
common human viruses that can have a long-lasting impact on the body's immune
system. Immune-compromised patients who receive HSCT, especially from
mismatched donors or matched but unrelated donors, may be at higher risk of
developing EBV-lymphoma than other patients with immune deficiencies. Previous
studies have suggested that EBV-lymphoma occurs most often in the first few
months post-transplant.

The researchers hypothesized that aggressive EBV-lymphomas may be more
responsive to control or eradication with EBV-specific cytotoxic T lymphocyte
(CTL) treatment (CTLs are highly specialized white blood cells that build the
body's defenses against disease). To test their theory, the team infused
EBV-specific CTL lines into two groups of patients: those who were undergoing
HSCT and were at high risk of developing EBV-lymphoma, and patients who had
already developed lymphoma. The study reported that CTL treatment successfully
prevented the development of EBV-lymphoma in all 101 patients in the at-risk
group who received the therapy prophylactically and achieved sustained
complete remission in 11 of the 13 patients (80 percent) treated
therapeutically (those who already had the disease).

"Therapy with EBV-specific CTLs was effective for these severely
immunocompromised patients. The CTLs successfully reached tumors, multiplied,
and were able to kill the tumor cells," said lead study author Helen Heslop,
MD, of the Center for Cell and Gene Therapy at Baylor College of Medicine, The
Methodist Hospital, and Texas Children's Hospital.

While the successful outcomes result from a number of factors in the study,
the researchers attribute some of the success of the trial to timely
treatment. The CTL lines were infused soon after stem cell transplantation,
when the existing white blood cell count was still low and was not quickly
regenerating, allowing the infused cells to more quickly multiply and mediate
anti-viral and anti-tumor effects. In addition, by marking and tracking the
CTL genes, the team was able to demonstrate that the cells could survive for
up to nine years in the body, conferring long-term protection.

With strong clinical outcomes, the study team is working to determine the most
appropriate role and timing for CTL infusions. Some newer therapies (such as
monoclonal antibodies) offer prophylactic and therapeutic options, but,
despite their availability, they cannot offer long-term protection. Therefore,
treatment with CTLs may be reserved for the highest risk patients - those with
a diagnosis of immune deficiency or a history of EBV-lymphoma, or those who
develop elevated EBV levels after therapy with monoclonal antibodies.

Importantly, the study found that this type of therapy is not only effective,
but economically advantageous. A preliminary analysis showed that a
patient-specific CTL line can be manufactured, tested, and infused for
approximately $6,000, a cost that compares well with other modalities used in
the treatment of EBV-lymphoma. Moreover, the team determined that it is
possible to manufacture cells in one location and ship them to another center
for infusion, with reproducible and consistent results and clinical outcomes.

"It's important to note that this promising therapy is not only effective, but
it is also a cost-effective option for high-risk patients," said Dr. Heslop.

Reporters who wish to receive a copy of the study or arrange an interview with
Dr. Heslop may contact Patrick C. Irelan at 202-776-0544 or
pirelan@hematology.org.

The American Society of Hematology (www.hematology.org) is the world's largest
professional society concerned with the causes and treatment of blood
disorders. Its mission is to further the understanding, diagnosis, treatment,
and prevention of disorders affecting blood, bone marrow, and the immunologic,
hemostatic, and vascular systems, by promoting research, clinical care,
education, training, and advocacy in hematology. ASH provides Blood: The Vital
Connection (www.bloodthevitalconnection.org), a credible online resource
addressing bleeding and clotting disorders, anemia, and cancer. The official
journal of ASH is Blood (www.bloodjournal.org), the most cited peer-reviewed
publication in the field, which is available weekly in print and online.

SOURCE American Society of Hematology

Patrick Irelan of the American Society of Hematology, +1-202-776-0544,
pirelan@hematology.org